OCaml implementation of operations in Program Algebra

Taddeus Kroes 23418c16e1 Added better error checking 11 rokov pred
.gitignore 9340893b20 Added basic PGA parser and printer 11 rokov pred
Makefile 9340893b20 Added basic PGA parser and printer 11 rokov pred
parse.ml 23418c16e1 Added better error checking 11 rokov pred
pga.ml 23418c16e1 Added better error checking 11 rokov pred
stringify.ml 23418c16e1 Added better error checking 11 rokov pred
types.ml 23418c16e1 Added better error checking 11 rokov pred