o.c.scan: Remove SetCommand.toXML()

Was left over from back when each command had toXML()
o.c.scan: Support String in WaitCommand
o.c.scan: Quote WaitCommand value if String
o.c.scan.scantree: List properies in order even if more than 10
o.c.scan.scantree: Quote string-or-double values if they're a string
o.c.scan: Extract StringOrDouble handling
o.c.scan: Increment version numbers
Merge pull request #549 from ControlSystemStudio/bug476

Scan: Support strings (enum) in 'Wait' command