Fixed HYDURLFormatter to not crash on non-strings.

Closes #9.
Added HYDUUIDFormatter.

Allows conversions between UUIDs and strings using:

- HYDUUIDFormatter
- HYDMapUUIDToString
- HYDMapStringToUUID

Also refactored HYDSetError to HYDSetObjectPointer and can
be used for more than just HYDErrors.

Closes #5.
Refactored code.

- Used HYDSetObjectPointer in more locations.
- Used HYDLocalizedStringFormat in more locations.