Merge branch 'ray_tracing' into multimed

* ray_tracing:
  - added create_vector function for easier re-use of dot and modu functions in ray_tracing - refactored ray_tracing using the dot, modu, and create_vector
  - fixed the error in lsqadj.c of modu ( ) function
  - simplified and shortened lsqadj.c after the comment of Yosef on ray_tracing pull request - vector functions are now clear and argumented - to be used in ray_tracing
  - removed s2 and reused the unit_vector from lsqadj.c to define direction unit vector
  - fixed the mistake in the expected values line
  - fixed indentation replaced by 4 spaces - moved unit_vector to lsqadj.{c,h} - added test_unit_vector to check_lsqadj.c
  removed some unused lines
  fix of glass interface bug

Conflicts:
	liboptv/include/ray_tracing.h
	liboptv/src/ray_tracing.c
	liboptv/tests/check_ray_tracing.c
- changed indentation in multimed.c
- updated the trans_Cam_Point to return the Exterior as is, except the x0,y0,z0
- merged ray_tracing branch
Merge branch 'multimed' into epi

* multimed:
  - changed indentation in multimed.c - updated the trans_Cam_Point to return the Exterior as is, except the x0,y0,z0 - merged ray_tracing branch