hoodlum-parser

Contains the LALRPOP parser code to cache its build between hoodlum changes.

lalrpop is not installed or required by the build step. Instead, it is generated manually the update_parser.sh script when the src/hdl_parser.lalrpop file is changed. This creates a hdl_parser.rs.gz file which is extracted by the build.rs file. This keeps the archive and git repository size small, doesn't require the end user to build LALRPOP or use the generation step, and overall speeds up development.