imaginary acker, verified Control Law examples

The Control Law examples have been checked against Matlab/Simulink.
All issues have been fixed and they both now agree.

In some cases the 'place' function produces imaginary values
in Matlab whereas it doesn't in Octave.  This can be seen
with cl_ex82 or cl_ss512 when they use 'place' in Matlab.
To make sure this problem is avoided 'myacker' is now used
for all cases and it also removes any non-real values.

A 'misc' directory has been added as a place to put general examples.