Accelerated qpOASES QProblem class...

... In particular, I optimized the method
QProblem::setupCholeskyDecompositionProjected, which was quite
inefficiently coded -- bottleneck for a bit larger cases with not so
many constraints. This should be tested if it really pays off for really
small problems.

For an equ. constrained QP with nv = 183 and nc = 9 a speedup
of cca 42% was observed.