Rewrite ATL parsing for better parse errors and more flexibility

[NicEastvillage]

This PR rewrites the ATL parser. Instead of using pom it is now a handmade lexer and parser. This PR is the first step towards #42, #104, #190.

This PR includes the following:

• Replaces the ATL pom parser with handmade Lexer and Parser.
  • The Lexer and Parser is designed to be able to parse LCGS too in the future.
• Adds better parsing and semantic analysis errors. See below.
• Changes disjunction and conjunction in ATL from & and | to && and ||, respectively, to be consistent with LCGS.
• Removes JSON CSG/ATL query support (Its rarely used anyway).

Example of new error messages:

[falkecarlsen]