Update MacOS X dependency build.

- use $NUMCPU for parallel build
- don't always rebuild libs when already installed
- switch to Qt 5.3.1 and disable most modules
- switch to eigen 3.2.1
- fix build order for ragel (needed by harfbuzz build)
Merge pull request #897 from openscad/macosx-build-fix

Update MacOS X dependency build.
Add version output to text examples and fix viewport orientation.
Merge pull request #898 from openscad/update-text-examples

Add version output to text examples and fix viewport orientation.
Save original $fn value for CSG output.
Lower number of segments generated for bezier path.
Handle $fn, $fa and $fs for CSG output.