Merge branch 'levelemblems' into 'master'

Level completion emblems

Simple port of something I made for a 2.1 exe mod that Mystic mentioned needed doing on the 2.2 Priorities topic (http://mb.srb2.org/showpost.php?p=790613&postcount=4). Adds emblem type "map", which gives you an emblem upon beating the map it's for.

Var sets specific condition flags on top of normal completion; 1 or ME_ALLEMERALDS for all Chaos Emeralds, 2 or ME_ULTIMATE for Ultimate mode, and 4 or ME_PERFECT for Perfect Bonus. These can be combined with each other, but they do not all need to be done in one shot; an Ultimate + Perfect emblem isn't impossible as they can be done in separate runs. (This can easily be toned back down to a single choice/removed entirely if requested; these were added simply because it was easy to implement for modders.)

Criticism on the way it's coded and/or how it is implemented is highly encouraged. Test wad is <root>/TehRealSalt/levelemblems.wad, pre-compiled exe is <root>/TehRealSalt/levelemblems.exe.

See merge request !74