Distribute Preferences

We've added an environment variable, VRED_PREFERENCES_OVERRIDE, and command line parameter, -preferencesOverride, for including a config file containing a subset of preferences to overwrite the local preferences for the session upon startup.

Create an .xml subset preferences file and note its location.

Define the preference file to overwrite the local preferences upon startup, such as:

<?xml version="1.0"?>
<!DOCTYPE VRED>
<message id="0" type="VRED" version="0.80000001">
 <key name="Annotation font color" type="OSGColor4f">1 0 0 1</key>
</message>

Define the location for the file giving the command line parameter, such as:
```
VREDPro.exe -preferencesOverride="e:\\preferences.xml"
```
Define the location for the file setting the environment variable, such as:
```
set VRED_PREFERENCES_OVERRIDE=e:\\preferences.xml
VREDPro.exe
```