chore(model import): remove unused check
fix(import): do not move flow nodes on lane import
test(layout): add sequence flow layout test
impr(lane resize): allow diagonal resize, fix boundary move

Changes:
- lanes may be resized diagonally, discarting the horizontal resize
amount
- boundary event is properly moved during resize of a lane / pool

Closes CAM-523, CAM-522, CAM-521