TodoExtras language package

Extra syntax highlighting for TODOs. Each category is colour coded as below:

INFO IDEA HACK TASK NOTE - #055178

TODO FIXME DEBUG REMOVE OPTIMISE REVIEW REFACTOR UNDO CLEANUP CHANGE CHECK VERIFY - #a28500

INVARIANT PRE-CONDITION POST-CONDITION ASSUMPTION ASSERTION - #980096

CHECKED VERIFIED DONE MOVED FIXED REVISED - #649800

UNREACHED DEPRECATED REDUNDANT WARNING - #bd4d03

BUG ERROR BROKEN - #980400