Box Selection Changes

I redid the implementation for the Box Selection because the Solver method only added shapes that had been crossed over by the mouse. The new implementation creates a selection rectangle and uses that to check the shapes that are contained inside the selection (for left-to-right selection) and which also cross it (for right-to-left selection). The selections are displayed in a new Property Grid tab.

Aside from these changes, I made some improvements to the selection code for single shapes and for solids – it’s not necessary to box select a solid to change its properties.

I am now testing and fixing bus to prepare for the release.