Remove charesc, reinstate a more restricted dashes and tweak the definition of reservedop.

This makes the Lambda1 test pass the parser and the syntax highlighting for it is not obviously wrong.
Add parser support for mid-file pragmas.
Make the naming scheme of tests more future-proof before it's too late.

Also indent the ParserTest module to be consistent with indentation in other files in the project while I'm there.
Add the necessary plumbing for registering cabal files and giving them a proper icon.
Merge branch 'cabal-plumbing' of github.com:pjonsson/intellij-haskforce into pjonsson-cabal-plumbing
Update README.md