This commit introduces some changes in the architecture and some new features.

- Features:
* Support for Executing a script when loading a profile
* Removed a tab and small UI refactoring
* Chooser for polling system

- Architecture:
Abstraction of the polling system.
It is now selectable, and user will have a choice of using the traditional polling method, the widget grabber method, or the XSync based method. The XSync method is already in, but untested and unstable, though still not selectable.