Merge pull request #299 from lbl-srg/openmodelica

Merge openmodelica branch
Added Tolerance
Corrected type of tauIR.
Merge pull request #300 from lbl-srg/openmodelica

Merge openmodelica branch
Changed assignment of R.

This is for OpenModelica.
Merge branch 'openmodelica'
Bugfix for sky cover if not obtained from weather file.
Merge branch 'master' into openmodelica-weather