Complete implementation of NSScanner (#2582)

* Complete implementation of NSScanner
- Implemented the following functions/properties:
	- locale
	- copyWithZone:
	- localizedScannerWithString:
	- scanDecimal:
	- scanHexDouble:
	- scanHexFloat:
- Added unit tests for NSScanner (there were none, including for previously implemented features)
- Fixed a number of edge cases that were incorrect

Fixes #2083

* - Rewrote most NSScanner scan<Numeric> or <HexNumeric> functions using CRT functions
- Changed NSScanner to prefetch all characters in the string at init
- Added tests that check for differing behaviors between 32-bit and 64-bit types
- Misc CR feedback

* - CR feedback
- Renamed the states in scanHexDouble to reflect the current expected state rather than previous state

* rebased, made NSInteger safer