Start doc with install instructions using catkin
Doc of drone_stateestimation + quick start
some fixes in doc
some fixes in doc
fix images in doc
Doc for drone_autopilot
Doc for drone_gui
Doc: add tricks

The doc is more or less done.
However, a lot of things have been copied from .txt file or ROS wiki.
Should be checked
Delete readme_gui.txt
Delete readme_autopilot.txt
Delete readme_tricks.txt
Merge pull request #21 from tum-vision/doc-markdown

Doc markdown