Add EnvVariable class.
Remove exclamation mark from quoted strings.

Rationale: Doesn't need to be quoted!
Clean up unused methods.

Also add new method to create variables.
Add new class for parsing module files.
Finish initial implementation of loading/unloading.
Update README to reflect new capabilities.
Fix all issues so that Python 2.6.x, 2.7.x and 3.x are supported.
Increment version number.