Quick feasibility test for #304
enable mingw64 cross build (alpha stage)
enable both win32 and win64 build and upload (beta level) from same script
tweaks to improve build. alos update about.html docs
fix eigen bugs mingw32/64
improve mingw build, make rm silent
reduce flood of eigen warnings on mingw build
gcc warning off, eigen3 mingw build
url bugfix
if .com fails, stop build. also stop using make || make
credit tony theodore
zip silent
allow 'upload only' and 'dryrun' debugging options
update readme
bold a single about box line
Merge branch 'master' into issue341

Conflicts:
	scripts/builder.sh
Added recursion example. Fixes #346
Added tests for linear extrude with scale. Should mostly fix #273
Merge branch 'master' into issue304
make dependency build work for OpenCSG without qmake