This commit corrects errors in the Install script that prevent the successful
building of the full system.  These changes were made by Joe Clarke.

No changes to source code.  A full build was successfully performed on Win 7/Cygwin.
Added bFirst_call_erv boolean variable to flag first call to ERV model.
This allows creation of new reporting variable to hold and eventually report the electricity consumption of the ERV.
Added ERV model: routines ERVInit() and ERVOperation() in CentralVentSys.F
Made change to existing CVS models
- Subroutine MECH_VENT_CONTROL() now has three outputs
	+ ZONE_mechvent_cond, the equivalent UA value for ventilation sensible load
	+ ZONE_mechvent_moistFlow, the equivalent flow of ambiant air resulting in the same moisture flow as transported by the supply airstream
	+ ZONE_mechvent_airFlow, the ventilation airflow
- Made changes to MZVENT() in subsys.F so that:
	+ ZMBI(ICOMP,1) corresponds to a flow of ambiant air carrying the same moisture into the zone as the ventilation supply airstream
	+ and ZMBI(ICOMP,4) corresponds to the flow of dry air out of the zone
- Changed the logic behind the temperature control of CVS: CVS now OFF when ambient temperature between T_low and T_high
- Moved zone fractions calculations to the initialisation of the CVS
- Switched exhaust air conditions calculations from the conditions of AIM2_ref_zone to a zone volume average: routine ZONEAVG(Flag)
- Grouped initialisation actions common to all CVS systems into a CVSCommonInitialisation() routine to facilitate future changes

For details of these changes, their justification, and the testing (including the ESP-r Tester), see report:
	Pinel P., Development of an ERV model for ESP-r, Submitted to NRCan, 2014
Merge branch 'patrice_ERVModel' of https://github.com/ESP-rCommunity/ESP-rSource into patrice_ERVModel