Allow default loading of more than one Instrument Parameter File

[OwenArnold]

Instrument Parameter Files shipped with Mantid, with the name InstrumentName_Parameters.xml, that live in the instrument directory are automatically loaded when mantid loads data for a specific instrument.

So e.g. if we have in the instrument folder:

HRPD_Instrument_1.xml
HRPD_Instrument_2.xml
HRPD_Instrument_3.xml
HRPD_Parameters.xml

Then when any of the HRPD_Instrument_#.xml are loaded HRPD_Parameters.xml are then subsequenctly loaded.

Expand this so that if the instrument folder contains the files:

HRPD_Instrument_1.xml
HRPD_Instrument_2.xml
HRPD_Instrument_3.xml
HRPD_Parameters.xml
HRPD_Parameters_2.xml

then for this example HRPD_Parameters.xml is loaded after HRPD_Instrument_1.xml and HRPD_Instrument_3.xml are loaded and HRPD_Parameters_2.xml is loaded after HRPD_Instrument_2.xml.

Hence if a parameter file with a matching name exist than it takes precedence to the 'default' parameter file (which in the above example is HRPD_Parameters.xml)

Once implemented update IDF wiki accordingly

[OwenArnold]

This issue was originally trac ticket 5635