support modern libqhull libraries

The module was renamed from 'qhull' to 'libqhull'
and therefore geometric_shapes fails to compile on up2date systems.

This commit adds a proper cmake test module for various qhull
versions (taken from pcl) and passes the detected version on
via a config file. That way the resp. correct headers are included.
Merge pull request #2 from v4hn/libqhull-support

support modern libqhull libraries
fix linking for old qhull versions; remove use of config file
0.3.3
fix tests
add shapes::computeShapeBoundingSphere() function
fix bug in box sphere calc
fix cylinder bounding sphere calc.
fix compile bug in computeShapeBoundingSphere for cylinder.

Also change variable names for clarity.
add unit tests for computeShapeBoundingSphere()
place generated config.h in build tree, not src tree.
Merge pull request #3 from acornacorn/master

Add function to compute bounding sphere of a shape