Добавлено выделение редактируемого лэйбла по f2

По нажатию F2 при выделенном блоке должно включаться редактирование
первого редактируемого лейбла на сцене для этого блока
Edited selection of the label by pressing F2
Merge branch 'master' of https://github.com/artbez/qreal
changed code in conformity with stylegide
fixed a bug
Supported attribute "override" for ports.
Small remarks in supported "override"
Supported attribute "override" for ports.
merge branches and removal conflicts
merge branches [2]
supported generalizations for "pictures" and "labels"
Merge branch 'master' into override
Some bugfixes:
- swaped real and unreal update intervals;
- wheels in TRIK robot picture moved to back;
- 2D model is now again automaticly shown on interpretation start
- Repaired draw line and circle blocks
- Fixed linker`s floating segfault
Merge branch 'master' of github.com:qreal/qreal into robots
Removed color enumerations, used QColor(QString) instead
some modifications for "label"
Merge branch 'robots' of github.com:dvvrd/qreal into robots

Conflicts:
	plugins/robots/interpreters/commonTwoDModel/src/engine/view/d2ModelWidget.h
Fixed incorrect rotation axis point
Fixed automatic centering on robot when returning it to far initial position
Corrected items position in examples