Started reformulating the model.

This is for #234.
Removed the assert.
Corrected type of input argument.
Change algorithm to equation and corrected size declaration.
Corrected class of material
Merge pull request #299 from lbl-srg/openmodelica

Merge openmodelica branch
Removed weaBus.sol for OpenModelica.

Removed the expandable connector sol from the expandable connector
weaBus as this construct does not work in OpenModelica.
Deleted the expandable connector SolarSubBus.
Renamed the following variables on the weather data bus:
sol.zen -> solZen
sol.dec -> solDec
sol.alt -> solAlt
Deleted SolarSubBus.mo
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
Set Tolerance=1E-8.
Change der_temperature_u for OpenModelica.

This commit changes the function argument to use single elements rather
than a record.
Merge branch 'openmodelica' into openmodelica-weather
Updated release notes and conversion script.

This is for the update of the weather data bus.
Merge pull request #301 from lbl-srg/openmodelica-weather

Openmodelica weather bus compatibility