Eliminate warnings on MSVC 2013

Note that this required ignoring a few warnings with pragmas, changing the
parameter type and return types of std::string::find functions to size_t
from int and a new global warning disable on MSVC.

I've managed to avoid global warning disables up to this point in the
code, but I don't see a way around the "decorated name too long (C4503)" warning.

Closes #100

include/chaiscript/chaiscript_stdlib.hpp

@@ -38,7 +38,5 @@ namespace chaiscript
   };
 }
 
-
-
 #endif