Fixed bug, so that the gramian for the trajectory planning can be computed also for instable systems

Function to compute the transition for a state-space system from x0 to x1. The transition is computed on the basis of the gramian controllability matrix

Added symbolic evaluation of quantity.Symbolic. (This is necessary for some strange functions, see e.g. the corresponding unittest)
Simplified the "isempty" check for quantities

misc.struct & misc.getfield & misc.nameValuePairRemoveDots: new methods for parsing name value pairs into structs of structs

Added converter of quantity.Discrete to quantity.Function: a linear interpolation is used as valueContin$

Added help information for the plotEigenvalues function
Modified definition of signals.Piecewise

Important performance update transz_fast_nDim: matlab's matrix multiplication becomes very slow for large vectors. However, elementwise multiplication is ultra fast!
Example: a = ones(20000,20); b = ones(20,20000);
Now c = a*b is very very slow compared to
d = sum(a.'.*b,1)!