Resolve issue 3166.

These changes decode valid SIGHASH types on signatures in assembly (asm) representations of scriptSig scripts.
This squashed commit incorporates substantial helpful feedback from jtimon, laanwj, and sipa.

src/script/script.cpp

@@ -8,16 +8,6 @@
 #include "tinyformat.h"
 #include "utilstrencodings.h"
 
-namespace {
-inline std::string ValueString(const std::vector<unsigned char>& vch)
-{
-    if (vch.size() <= 4)
-        return strprintf("%d", CScriptNum(vch, false).getint());
-    else
-        return HexStr(vch);
-}
-} // anon namespace
-
 using namespace std;
 
 const char* GetOpName(opcodetype opcode)
@@ -237,26 +227,3 @@ bool CScript::IsPushOnly() const
     }
     return true;
 }
-
-std::string CScript::ToString() const
-{
-    std::string str;
-    opcodetype opcode;
-    std::vector<unsigned char> vch;
-    const_iterator pc = begin();
-    while (pc < end())
-    {
-        if (!str.empty())
-            str += " ";
-        if (!GetOp(pc, opcode, vch))
-        {
-            str += "[error]";
-            return str;
-        }
-        if (0 <= opcode && opcode <= OP_PUSHDATA4)
-            str += ValueString(vch);
-        else
-            str += GetOpName(opcode);
-    }
-    return str;
-}