added installation of qt-sdk to travis config, in hope that it will fix builder
added some weird linux stuff
Added 2D model and sensors configuration saving into repo
Merge branch 'installer' of github.com:qreal/qreal into 2dModelIntoRepo
Merge branch 'travis' of github.com:qreal/qreal into 2dModelIntoRepo
Fixed sensor position reinitting wth its type modification;
Restored scene updating on mouse events
Merge pull request #671 from dvvrd/2dModelIntoRepo

2D world model storing