fixes #0001684: Sweep ignores the list of subshapes
Merge branch 'master' of ssh://git.code.sf.net/p/free-cad/code
improve sweep output
support for point, vertex and object cache
use rounded floats if they safe digits

Sometimes the floats seems to be rounded to twelve decimal
places. we round them if it allows so safe digigts.
round angles
check for arc and do not explode edges
format radius