Use ANTLR4 for parsing text based formats

[Laupetin]

Currently all parsing of text based format is done via a self-made parser that I introduced to experiment with creating a parser.
Since I didn't have any theoretical background when doing this, all the terminology is not making any sense and it is also most likely has very poor performance compared to popular parser generators outputs.

Therefore it would probably be beneficial for code readability, reducing complexity and streamlining to use a more mainstream solution for parsing text based formats.
My personal preference here is ANTLR4 since I already have experience with it and I prefer it over flex/bison that the original games did make use of.