Add a .pylint confguration file.

* Restrict line length to 94 chars.
Restructure checking via .pylintrc.
Install submodule structure.

* Activate flagging of import errors (F0401).
Flag access to absent member (E1101).

* Suppress warning in test folder caused by sure monkey-patching.
Flag bad whitespace (C0326).

* Suppress warning inside lexer setup.
Flag pointless statements (W0104).

* Suppress warnings due to sure.
Flag expressions not assigned (W0106).

* Replace some invocations of sure with unittest methods.
Merge pull request #73 from Renelvon/stricter_pylint

Install stricter pylinting