FMod - Number format consistency

"Gridlock" reported to me via IRC that some Abiathar tools, notably the Tile Property Modifier, always show tile IDs and coordinates in decimal no matter what the ShowInHex settings are. That is indeed a problem, since it makes it difficult to see whether you're looking at the right tile/location. I added a new API function to determine the appropriate display string for a number and have started updating the StandardTools extension to take advantage of it.