Bug fixes for IRAF plugin and intensity map

	modified:   RGBMap.py
	modified:   Settings.py
	modified:   ginga.py
	modified:   gtkw/plugins/Info.py
	modified:   gtkw/plugins/Preferences.py
	modified:   imap.py
	modified:   misc/plugins/IIS_DataListener.py
	modified:   misc/plugins/IRAFBase.py
	modified:   qtw/plugins/Info.py
	modified:   qtw/plugins/Preferences.py

- fixes a bug where intensity map values were not mapped to ints correctly
- IRAF plugin now includes a special color map that is installed when
    images are displayed from IRAF
- tvmark plotted colors are now correct