Support x-sysdate/x-systime directives

[borgar]

Add support for system time/date overriddes:

• [$-F800] or [$-x-sysdate]
• [$-F400] or [$-x-systime]

Work done here:

• Added sysdate and systime properties to the LocaleData type.
• Added sysdate and systime values to every supported language (values mined from Windows Excel).
• Added a new locale directive parser which adds full support for both LCID and BCP styles.
• Fixes the codeToLocale table to use xx-XX over xx_XX syntax.
• Pattern parse/cache mechanism moved to own file.

Closes #43