trying to fix filter issues in swmr mode
Merge branch 'swmr' of github.com:FilipeMaia/owl into swmr

Conflicts:
	view2d.py
new stack object that shall take care of synchronous stack size changes during run time
incorporated a more central organization of the stack size. The smallest stack defines the stack size in the file loader. Every stack loaded has that size. I am having problems with the refresh method from time to time. Are there any restrictions when I am allowed to call it?
removed some debugging prints and resolved conflict.