Various improvements, anonymous free vars now works - fixes #288

The improvements contain:
  - Module `OldScopeEnv` removed (content integrated into `CaseCompletion`
  - Intermediate structures from the checking phases can now
    also been dumped to stdout
  - Compiler options for additional dump targets added
  - Dumps now output the data type instead of its pretty printing
    to provide more information
  - Anonymous free variables are now renamed correctly
  - Erroneous shadowing warnings are fixed (was due to wrong renaming)