Feature: Window support

[s1hofmann]

Short overview
Provide access to OS windows

Use case
As a user I want to be able to retrieve window data like it's position, title or size.

Detailed feature description

• It should be possible to retrieve a list of open windows
• It should be possible to retrieve the currently active window
• It should be possible to retrieve a window's size and position
• It should be possible to retrieve a window's title