Add SCRIPT_VERIFY_MINIMALDATA (BIP62 rules 3 and 4)

Also use the new flag as a standard rule, and replace the IsCanonicalPush
standardness check with it (as it is more complete).

src/test/transaction_tests.cpp

@@ -34,6 +34,7 @@ static std::map<string, unsigned int> mapFlagNames = boost::assign::map_list_of
     (string("DERSIG"), (unsigned int)SCRIPT_VERIFY_DERSIG)
     (string("LOW_S"), (unsigned int)SCRIPT_VERIFY_LOW_S)
     (string("SIGPUSHONLY"), (unsigned int)SCRIPT_VERIFY_SIGPUSHONLY)
+    (string("MINIMALDATA"), (unsigned int)SCRIPT_VERIFY_MINIMALDATA)
     (string("NULLDUMMY"), (unsigned int)SCRIPT_VERIFY_NULLDUMMY);
 
 unsigned int ParseScriptFlags(string strFlags)