Bugfixes and improvements related to method 3 of lyapunov_symm.m

- the function was called with the wrong input argument for this case (Q instead of R*Q*R'), crashing with incompatible matrix dimensions
- the persistent variable X was not updated when the size of it changed, leading to crashes when estimation is followed by calls to DsgeSmoother.m where the state-space is different
- Also eliminates the printed output in lyapunov_symm.m that could not be turned off and clutters estimation
Add unit test for Lyapunov solver

- tests whether they run within a mod-file
- tests whether they yield the same result for a simple state-space model
Removed useless input (complete commit 438a671c3873e5c4e1bb02a54080e930fbc11886).
Fixed test introduced in commit and removed binary file.

Test was introduced in b11d14498aadac17c08b08dd80b6daf7dec9e340.

The binary  file was a mat  file containing a posterior  mode, and the
second estimation must be run iff the control toolbox is available.
Add a parameter to the lyapunov_symm routine (debug mode).
Removed "Do pure Lyapunov tests" section.

This should be done in the lyapunov_symm routine.
Added unit tests for lyapunov_symm routine.