More formatting options

[Xenapte]

This commit adds format and formatDateTime to Starscript. Yes, I know one of the selling points of Starscript is to be faster than String.format, but sometimes you do need more formatting options.

format(fmt, ...args)

Adds arbitrary formatting by calling String.format. This can be considered as a fix to [#7] too.

formatDateTime(fmt)

Calls SimpleDateFormat because currently Starscript date and time don't allow the user to choose a custom format.