1) fixed bugs when no estimated parameters are declared;
2) fixed bug for the ML base (bayestopt_.pshape==0);
3) make more transparent the error when the model does not solve at prior_mode or  prior_mean;
4) when prior_mean or prior_mode fail, try 50 times with randomly generated samples from the prior before interrupting identification.

This commit fixes issues related to fabiac forum request and subsequent discussion with Johannes.

http://www.dynare.org/phpBB3/viewtopic.php?f=1&t=4402&p=10771&hilit=identification&sid=64c6f9d987a2641e79dd5722137eb483#p10771
1) trap the case where the model does not solve for any parameter values in the MC sample;
2) fixed initialization of alpha2_stab;
1) better trace all cases when the model does not solve, classifying cases according to info output of dynare_resolve;
2) trap the case of memory allocation limit for too large model undergoing to reduced form mapping
Trap the cases where the state space matrices are not stored for memory allocation issues
[to be fixed later by breaking the big matrix stored ...]
bug fix in call to priordens;
Merge pull request #327 from rattoma/master

Identification and sensitivity fixes