With `pip install -e` the generated .egg-link file gets preferred over
any normally installed distribution, and `pip uninstall` will first
remove the egg-link before the normal package.
This also includes a rework for error recovery in the parser. This is now just possible for file_input parsing, which means for full files.
Includes also a refactoring of the tokenizer. No more do we have to add an additional newline, because it now works correctly (removes certain confusion.
- add sys_path= kwarg to Script & Evaluator constructors
- store sys_path for each evaluator instance
- replace get_sys_path with get_venv_path
- get_venv_path: use addsitedir to load .pth extension files
- get_venv_path: look for egg-link files in all directories in path
