move spline.py to tools, remove trwxml test
remove tests from tfun.cpp
move examples to doc/ folder
Move tfun.cpp to docs/example/ and move tmod.cpp to apps/lenstool/lenstool.cpp
Add some basic test routines to tests/ folder
Update docs and cmake to work with new folder structure created in previous commits
Two more checks to avoid invalid input values in asin() function
Enhance and update lenstool
Documentation updates
Properly show lenstool build status CMake messages