[tests] adds prototype functional testing of demos
[tests] fixup functional test runner to close child procs (GUIs)

also allows expected failures in GUIs when PySide is missing
[algorithms] fixes error in gram_schmidt call
[tests] potentially fix thermalblock_gui functional test
[tests] new tests for newton-algo and vtkio
[algorithms] fixes newton default arg handling
[tests] new one for lincomb function
[tests] new ones for extension algs + parabolic_demo
[algorithms] fixes unhandled default arg in implicit euler timestepper
[demos] allow toggling Rect/TriaGrid in cg demo
[tests] also test Q1 ops via cg demo with RectGrid
[tests] allow running demo tests from outside pymortests package
[tests] revamp MonomOp to use numpy's Polynomial class internally
[operators] lincomb op gets a __sub__
[tests] new ones for lincomb op_base
[tests] couple more demo runs with diff arguments

parabolic is already included in demos now
[tests] new gmsh test that calls all grid tests with gmsh instance
[tests] new test for patch visualizers
[tests] allow simplified_engquist_osher flux in burgers demo
Merge remote-tracking branch 'origin/master' into functional_tests

Conflicts:
	src/pymor/algorithms/timestepping.py