Merge pull request #11 from kuyon/develop

zoom fix + add polyline
Merge pull request #12 from kuyon/develop

polyline null catch
Support the latest mruby for #df780ae of mruby/mruby.
Add command "hide".
Add command "sew".
Add command "explode".
Add command "bgcolor", but faild to change the color with 3 values(non-gradient backcolor).
Add command "intersect".
Cleanup.
Add TopoDS* headers.
Disable compile non required source.
Remove unrequired source.
Change dropdown-menu for materials.
Change terminal.