added RVO2_2D to arl_ROA
Added LQR functions, need to find value for mg, Need tilt set in nav_callback
ORCA2.cpp contains ORCA with stacked quads and a LQR controller. Need tilt values in nav_data and better estimate of mg
Fixed dimensions of LQR cost matrix, added rotation to nav_callback, added correct weight estimate, ready for testing
updated CMake to use ORCA2.cpp instead of ORCA.cpp
made LQR matrices global, fixed rotation vars in nav_callback
Merge pull request #2 from damanfb/master

do it