Merge pull request #53 from AxTheB/master

More STLs and bit of cleaning.
Merge pull request #54 from AxTheB/master

Fix xends for bushings
Merge pull request #55 from AxTheB/master

Fix for Xend and skate bearings
copied endstop-holder from restructure branch, prusa i2 repository
made endstop holder parameteric and produce the correct ones according to smooth rod size
fix 624 idler bearing spacing
make number of segments configurable on small holes
added small_hole_segments to bushing and x-carriage as well
Add option to use chamfered endes instead of bevels
Merge branch 'master' of github.com:josefprusa/Prusa3