Replace uses of boost::filesystem with fs

Step two in abstracting away boost::filesystem.

To repeat this, simply run:
```
git ls-files \*.cpp \*.h | xargs sed -i 's/boost::filesystem/fs/g'
```

src/util.cpp

@@ -214,7 +214,7 @@ void OpenDebugLog()
 
     assert(fileout == NULL);
     assert(vMsgsBeforeOpenLog);
-    boost::filesystem::path pathDebug = GetDataDir() / "debug.log";
+    fs::path pathDebug = GetDataDir() / "debug.log";
     fileout = fopen(pathDebug.string().c_str(), "a");
     if (fileout) {
         setbuf(fileout, NULL); // unbuffered
@@ -353,7 +353,7 @@ int LogPrintStr(const std::string &str)
             // reopen the log file, if requested
             if (fReopenDebugLog) {
                 fReopenDebugLog = false;
-                boost::filesystem::path pathDebug = GetDataDir() / "debug.log";
+                fs::path pathDebug = GetDataDir() / "debug.log";
                 if (freopen(pathDebug.string().c_str(),"a",fileout) != NULL)
                     setbuf(fileout, NULL); // unbuffered
             }
@@ -511,9 +511,9 @@ void PrintExceptionContinue(const std::exception* pex, const char* pszThread)
     fprintf(stderr, "\n\n************************\n%s\n", message.c_str());
 }
 
-boost::filesystem::path GetDefaultDataDir()
+fs::path GetDefaultDataDir()
 {
-    namespace fs = boost::filesystem;
+    namespace fs = fs;
     // Windows < Vista: C:\Documents and Settings\Username\Application Data\Bitcoin
     // Windows >= Vista: C:\Users\Username\AppData\Roaming\Bitcoin
     // Mac: ~/Library/Application Support/Bitcoin
@@ -538,13 +538,13 @@ boost::filesystem::path GetDefaultDataDir()
 #endif
 }
 
-static boost::filesystem::path pathCached;
-static boost::filesystem::path pathCachedNetSpecific;
+static fs::path pathCached;
+static fs::path pathCachedNetSpecific;
 static CCriticalSection csPathCached;
 
-const boost::filesystem::path &GetDataDir(bool fNetSpecific)
+const fs::path &GetDataDir(bool fNetSpecific)
 {
-    namespace fs = boost::filesystem;
+    namespace fs = fs;
 
     LOCK(csPathCached);
 
@@ -576,13 +576,13 @@ void ClearDatadirCache()
 {
     LOCK(csPathCached);
 
-    pathCached = boost::filesystem::path();
-    pathCachedNetSpecific = boost::filesystem::path();
+    pathCached = fs::path();
+    pathCachedNetSpecific = fs::path();
 }
 
-boost::filesystem::path GetConfigFile(const std::string& confPath)
+fs::path GetConfigFile(const std::string& confPath)
 {
-    boost::filesystem::path pathConfigFile(confPath);
+    fs::path pathConfigFile(confPath);
     if (!pathConfigFile.is_complete())
         pathConfigFile = GetDataDir(false) / pathConfigFile;
 
@@ -591,7 +591,7 @@ boost::filesystem::path GetConfigFile(const std::string& confPath)
 
 void ReadConfigFile(const std::string& confPath)
 {
-    boost::filesystem::ifstream streamConfig(GetConfigFile(confPath));
+    fs::ifstream streamConfig(GetConfigFile(confPath));
     if (!streamConfig.good())
         return; // No bitcoin.conf file is OK
 
@@ -616,14 +616,14 @@ void ReadConfigFile(const std::string& confPath)
 }
 
 #ifndef WIN32
-boost::filesystem::path GetPidFile()
+fs::path GetPidFile()
 {
-    boost::filesystem::path pathPidFile(GetArg("-pid", BITCOIN_PID_FILENAME));
+    fs::path pathPidFile(GetArg("-pid", BITCOIN_PID_FILENAME));
     if (!pathPidFile.is_complete()) pathPidFile = GetDataDir() / pathPidFile;
     return pathPidFile;
 }
 
-void CreatePidFile(const boost::filesystem::path &path, pid_t pid)
+void CreatePidFile(const fs::path &path, pid_t pid)
 {
     FILE* file = fopen(path.string().c_str(), "w");
     if (file)
@@ -634,7 +634,7 @@ void CreatePidFile(const boost::filesystem::path &path, pid_t pid)
 }
 #endif
 
-bool RenameOver(boost::filesystem::path src, boost::filesystem::path dest)
+bool RenameOver(fs::path src, fs::path dest)
 {
 #ifdef WIN32
     return MoveFileExA(src.string().c_str(), dest.string().c_str(),
@@ -650,13 +650,13 @@ bool RenameOver(boost::filesystem::path src, boost::filesystem::path dest)
  * Specifically handles case where path p exists, but it wasn't possible for the user to
  * write to the parent directory.
  */
-bool TryCreateDirectory(const boost::filesystem::path& p)
+bool TryCreateDirectory(const fs::path& p)
 {
     try
     {
-        return boost::filesystem::create_directory(p);
-    } catch (const boost::filesystem::filesystem_error&) {
-        if (!boost::filesystem::exists(p) || !boost::filesystem::is_directory(p))
+        return fs::create_directory(p);
+    } catch (const fs::filesystem_error&) {
+        if (!fs::exists(p) || !fs::is_directory(p))
             throw;
     }
 
@@ -763,11 +763,11 @@ void ShrinkDebugFile()
     // Amount of debug.log to save at end when shrinking (must fit in memory)
     constexpr size_t RECENT_DEBUG_HISTORY_SIZE = 10 * 1000000;
     // Scroll debug.log if it's getting too big
-    boost::filesystem::path pathLog = GetDataDir() / "debug.log";
+    fs::path pathLog = GetDataDir() / "debug.log";
     FILE* file = fopen(pathLog.string().c_str(), "r");
     // If debug.log file is more than 10% bigger the RECENT_DEBUG_HISTORY_SIZE
     // trim it down by saving only the last RECENT_DEBUG_HISTORY_SIZE bytes
-    if (file && boost::filesystem::file_size(pathLog) > 11 * (RECENT_DEBUG_HISTORY_SIZE / 10))
+    if (file && fs::file_size(pathLog) > 11 * (RECENT_DEBUG_HISTORY_SIZE / 10))
     {
         // Restart the file with some of the end
         std::vector<char> vch(RECENT_DEBUG_HISTORY_SIZE, 0);
@@ -787,9 +787,9 @@ void ShrinkDebugFile()
 }
 
 #ifdef WIN32
-boost::filesystem::path GetSpecialFolderPath(int nFolder, bool fCreate)
+fs::path GetSpecialFolderPath(int nFolder, bool fCreate)
 {
-    namespace fs = boost::filesystem;
+    namespace fs = fs;
 
     char pszPath[MAX_PATH] = "";
 
@@ -850,9 +850,9 @@ void SetupEnvironment()
     // The path locale is lazy initialized and to avoid deinitialization errors
     // in multithreading environments, it is set explicitly by the main thread.
     // A dummy locale is used to extract the internal default locale, used by
-    // boost::filesystem::path, which is then used to explicitly imbue the path.
-    std::locale loc = boost::filesystem::path::imbue(std::locale::classic());
-    boost::filesystem::path::imbue(loc);
+    // fs::path, which is then used to explicitly imbue the path.
+    std::locale loc = fs::path::imbue(std::locale::classic());
+    fs::path::imbue(loc);
 }
 
 bool SetupNetworking()