Made special ei, si, mi, and oi numpy structure array.
This is for rapid speed-up of numpy array creation in target function.
Task #7807 (https://gna.org/task/index.php?7807): Speed-up of dispersion models for Clustered analysis.
Authored by: tlinnet 2014-06-10
Parent: [r23801]
Child: [r23803]
