- suggested fix for termination condition for ray computations that miss the target voxel due to discretization errors (current condition triggered too early in some cases, resulting rays fell short one (or two?) voxels)
- added more beams to test_raycasting
- still would need a test case that triggers the condition when it is needed (a ray missing the target voxel)
Fix unit tests for fixed raycasting behavior. New tests to catch old
bug, test "CastRay" now in "test_raycasting.cpp".

Conflicts:

	octomap/src/testing/CMakeLists.txt
	octomap/src/testing/unit_tests.cpp
Removing test "OcTreeIterator" from unit_tests.cpp, was superseded by test_iterators.cpp
and depended on previously-created file.
Fix paths for unit test files