GCC 4.9 Unsigned/Signed Comparison

GCC 4.9 catches unsigned/signed comparison errors that neither GCC 4.8.1 and Clang do.
Build Fix/Update

build.bat no longer uses a convoluted and non-portable path to GNU Make on Windows.
String Conversion to std::basic_string<T>

String objects are now implicitly convertible to std::basic_string<T>.
Floating Point Conversion Fixes

Fixed various floating point conversion bugs which caused erroneous successes, including:

- Conversion of the empty string to zero
- Conversion of strings with extra decimal places to numeric values obtained by simply disregarding the erroneous decimal place(s) and everything thereafter (i.e. "1.1.1" => 1.1)
- Conversion of strings with leading/trailing white space