Support ImageListObj in RibbonButton and RibbonButtonGroup

[mkromberg]

Allow setting of ImageListObj in RibbonButton and RibbonButtonGroup objects. Note that ImageListObj is an array in a RibbonButtonGroup. DemoRibbonTab2 has been updated to use this for one of each type of object:

{"WC":{"ID":"F1.TC.SF3.Ribbon.Item3.GroupItem1.StockExchangeButton","Properties":{"Caption":"UK","Event":[["Select",""]],"ImageIndex":2,"ImageListObj":"IL32","Size":12,"Type":"RibbonButton"}}} {"WC":{"ID":"F1.TC.SF3.Ribbon.Item4.GroupItem1.ButtonGroup1","Properties":{"Captions":["Denmark","Blue"],"Event":[["Select",""]],"ImageIndex":[1,1],"ImageListObj":["IL32","IL"],"Type":"RibbonButtonGroup"}}}

When support is added correctly, the buttons labelled "UK" and "DK" below should show flags instead of the current logos:

[mkromberg]

Tested August 10th: DK is showing a flag, but UK not. The relevant messages which should add the British flag are:

{"WC":{"ID":"IL32","Properties":{"Files":["/images/flags32/dk.png","/images/flags32/uk.png","/images/flags32/us.png"],"ImageCount":3,"Masked":2,"Size":[32,32],"Type":"ImageList"}}} {"WC":{"ID":"F1.TC.SF3.Ribbon.Item3.GroupItem1.StockExchangeButton","Properties":{"Caption":"UK","Event":[["Select",""]],"ImageIndex":2,"ImageListObj":"IL32","Size":12,"Type":"RibbonButton"}}}

The message that does work for the Danish flag is: {"WC":{"ID":"F1.TC.SF3.Ribbon.Item4.GroupItem1.ButtonGroup1","Properties":{"Captions":["Denmark","Blue"],"Event":[["Select",""]],"ImageIndex":[1,1],"ImageListObj":["IL32","IL"],"Type":"RibbonButtonGroup"}}}