Backported 2e3729ab2268f29ee4ff5898f629c4a10c2d6587 to master; redo assemblePath for Win. redo openscad.com to handle spaces in filenames
Editor: Implemented simple Find functionality

Conflicts:
	src/MainWindow.h
Editor: Reduce find panel bottom margin
Editor: Implement Search & Replace

Conflicts:
	src/MainWindow.h
Editor: Subtle UI Tweak

Return in the find or replace field will animate the triggered button
Editor: Fix bug where replaceAll could enter an infinite loop
Remove automatic validity check at end of render

In more complex cases, the final Nef_Polyhedron is_valid check() took up to 30 % of the total rendering time just to be able to say Valid: YES. In the case of cached geometry, the validity check was totally dominating the execution time when doing a render. This patch removes the automatic validity check, instead adding a menu command "Check Validity".

Conflicts:
	src/mainwin.cc
Moved % modifier handling from node to nodedumper. This makes nodes with % operators use the existing cache instead of recalculating the object