Moved the costly calculation of matrix_exponential of M1 and M2 out of for loop, in model ns_mmq_2site_mq.
Task #7807 (https://gna.org/task/index.php?7807): Speed-up of dispersion models for Clustered analysis.
Authored by: tlinnet 2014-06-20
Parent: [r24190]
Child: [r24192]
