octovis: do not hardcode absolute paths in octovis-config.cmake

Hardcoding abslotue install paths in octovis-config.cmake totally breaks
the cross-compilation: it makes impossible to be used in a sysroot because
the hardcoded paths are the ones of the target, whereas they should point
to the sysroot location.

This patch uses the CMake find_library and find_path to set the variables
OCTOVIS_LIBRARIES and OCTOVIS_INCLUDE.
octomap: do not build test program when tests are disabled.
dynamicEDT3D: allow to disable example build
cleanup trailing whitespaces