Efficiency & Cosmetic  changes related to the design  of bayestopt_ and
the computation of the prior density.

bayestopt_.p1 is always the prior mean
bayestopt_.p2 is always the prior standard deviation
bayestopt_.p3 is unchanged
bayestopt_.p4 is unchanged
bayestopt_.p5 [new field] is the prior mode
bayestopt_.p6 [new field] is the first hyper-parameter of the prior density
bayestopt_.p7 [new field] is the second hyper-parameter of the prior density
 
These fields are defined in  set_prior and are never changed after. In
the previous version of Dynare,  the hyper parameters of the densities
were  updated at  each iteration  of the  optimization routine  or the
metropolis.

Removed fields pmean and pstdev.

Vectorized the code in priordens.

Fixed the bug mentionned by Gianni. If a (logged) density is evaluated
outside the  prior domain, the  output of priordens if  minus infinity
(instead of a complex number).


git-svn-id: https://www.dynare.org/svn/dynare/trunk@2556 ac1d8469-bf42-47a9-8791-bf33cf982152