Make UDMF parser aware of escape sequences

This PR makes the UDMF and TRNSLATE parsers aware of escape sequences. This fixes an issue where, if a string in a TEXTMAP had quotation marks, the parser would incorrectly end the string early, potentially causing the map to be read incorrectly. Additionally, escape sequences like \n or \x85 will be correctly escaped in the parsed string.

Test map in vanilla:

Test map in this PR:

Test map used:
comment-test.wad