correct undo-redo when moving elements
undo-redo & linear ports
fix #1015
fix #1034
undo-redo support of edge context menu actions
reverse action undo-redo
link types generation and metaeditor support
change link type from context menu
line handler initialization
link types and repo
highlight ports available to connect link to
copy-paste support of link types
factory for line handlers
dosygen
Merge branch 'master' of https://github.com/qreal/qreal into links2

Conflicts:
	qrgui/umllib/private/lineHandler.cpp
	qrgui/umllib/private/lineHandler.h
	qrgui/umllib/private/squareLine.h
	qrgui/umllib/umllib.pri
style fixes
Merge pull request #1054 from Ashatta/links2

Улучшения линков