Fixed bugs which where the result of letting boundary simplices be unsafe editable.
Specify the removed and surviving node when collapsing an edge.
Simplified the collapse functions and the attributes of the surviving node is determined by weighting the attributes of the nodes adjecent to the collapsed edge. Also, the surviving node is guaranteed to be the one which is not unsafe editable.
Bugfix in collapse test.
Clean up in simplex getter functions.
Making a lot of the assertions in DEBUG mode only.
Ensures that unsafe editable simplices are not removed when an edge is collapsed.