Function mocTileCount( moc )

Description:
Returns the number of unique tiles within a given MOC.

If the given moc value does not represent a MOC (for instance no file exists or the file/string is not in MOC format) a warning will be issued the first time it's referenced, and the result will be 0.

Parameters:
moc (String)
a MOC identifier; a filename, a URL, a VizieR table name, or an ASCII MOC string
Return Value (long integer):
number of tiles in the MOC
Signature:
long mocTileCount(String)