v3.1.15 in beta ; generic/dimmer improvements

This set of changes on effects the generic / dimmer node, to address control in scenes, fast on/off, adding memory so normal on will return to the last on level.

Need to test so we know its not breaking for anyone.

Details:

1. changed ST to OL (on level)
2. send is now DON, DOF, DFON, DFOF, BRT, DIM, OL (send level)
3. accepts is now the same with OL setting the OL
4. added a "memory",
   1. DON uses the memory
   2. set at 100 initially
   3. persistent over reboot of ISY, plugin
   4. BRT, DIM, modify the memory, but if DIM to zero, sets to 10 so ON is never zero
   5. OL mods the memory but if zero sets to 10
   6. DFON does not affect the memory just sets level to 100
   7. DOF, DFOF sets level to zero, mods the memory if level not 100
   8. all seem to work for the programs as control / status
5. Have not tested scenes exhaustively, but should work for control for DON, DOF, DFON, DFOF
6. need to test more on effects for scenes for BRT, DIM, OL