Add EIGENPY_SITELIB_ROOT to customize sitelib install location.

Corrected PYTHON_EXT_SUFFIX usage.

Fix some operators in Geometry classes

cmake: sync submodule

eigenpyConfig.cmake: find absolute library paths for all required libs

As cmake expects absolute library paths, while pkgconfig provides lib names only (together with
LIBRARY_DIRS), one needs to find the full library path.

This fixes 7854c0fc.

Update Quaternion class with more constructors

cmake: sync submodule

Add CMake config using pkg-config internally

- MoveIt cannot make a new release right now with our bugfix due to people constraints
- We cannot roll back due to project constraints
- This adds a cmake config that internally uses the pkg-config. This will be replaced in the future with one with proper CMake targets

cmake: sync submodule

Fix issue for pkg-config export of the lib