Bug Fixing in Multiple Areas

In the last two days I've worked intensively on bug fixing.
Layers code did expose a problem of performance: the updating of layers visibility affected that some shapes (almost all scene, but they were affected all shapes that do have layer information attached) need to be (re)generated. As if you draw complex shapes (like boolean operations), they simply make NaroCAD to get slower and slower.
This problem was fixed, also some extra code that was running at switching actions was also moved. This exposed some other problems that were in code (like in a lot of cases that were involved overriding virtual methods, they don't call the base class methods, even those base class methods have some virtual classes).
Cut shape was also fixed in cases that selection was done from tree.
A small double delete key pressing leading to crash was also fixed.
Dimension on lines work as Dimension was restricted to work on shapes that do work with Dimension and for some reasons Line was not in them.
The last area that get some fixes was the arcs code that had some cases that do not work, and was fixed.