some unfinished code related to sensor settings synchronization
fixed bug with groups creation
Sensors configuration is now synchronized properly
added .txt to gitignore to stop spamming with usability statistics
Merge branch 'master' of https://github.com/qreal/qreal into sensors-synchronization

Conflicts:
	plugins/robots/robotsInterpreter/details/d2RobotModel/d2ModelWidget.cpp
Fixed too frequent sdf files re-reading
fixed styleguide
Merge pull request #1204 from qreal/sensors-synchronization

Sensors synchronization + Some optimizations for sdf-based icons