extended documentation of math library
* removed namespace cpp_pthread
* added method for matrix multiplication
* fixed error in vec2quat
* extended documention of camera library
improved test cases for camera library
removed deprecated methods from feature.(cpp|h)
*merged feature*_test to one file
*splitted hub_test.cpp in math_test.cpp and time_test.cpp
*unified naming for test suites
added method for cosine similarity