Metamodel and metaeditor extended with explosions entities
Added explosion binding to robots subprogram
Merge branch 'robots' of github.com:dvvrd/qreal into subprograms
Connections replaced with explosions in models
Removed old connections/usages mechanism;
Some of its parts replaced with explosion links
Merge branch 'robots' of github.com:dvvrd/qreal into subprograms
Some fixes caused aseertation faults
Small refactoring: something migrated into view/private
Elements were forbidden to have multiple explosions
Finished old-style explosions implementation
Merge branch 'robots' of github.com:dvvrd/qreal into subprograms
Merge branch 'robots' of github.com:dvvrd/qreal into subprograms
index on subprograms: 9373564 Merge branch 'robots' of github.com:dvvrd/qreal into subprograms
Some palette refactoring:
	moved into separate folder;
	new class with double-palette behaviour encapsulation.
Some extended refactoring
Added some basic high-level explosions handlers;
Added global undo-redo stack;
Critical fixes in concrete element-based undo/redo commands
Fixed bug causing desynchronization of logical/graphical model explorers
Some refactorings in models
fixed #840, deleting shortcut, added default size of columns
Added explosions undo/redo;
Some fixes for undo stack