LanguageParser excluded from various static code analysis tools

[Boudewijn26]

Because LanguageParser is a special class, implemented in a sort of declarative manner instead of the typical imperative Java style, the code style heavily deviates from the CheckStyle config.

Also because LanguageParser is wrapped by parboiled in a rather fancy manner, findBugs is also excluded, because it doesn't actually find bugs in LanguageParser, even when it thinks it does.