Issue 161: Adding 16-channel custom dimming expansion support

Adding support for the 16 channel dimming module to ReefAngel.DCPump for powerheads, ReefAngel.PWM for lights, and Wifi for overrides and returning the values in XML and JSON output.  

Values in each channel will be reported through the wifi as percents, but LED slopes internally will use 12-bit integers for the utility functions in RA_PWM.

Also added it to EM1 for eventual reporting on the LCD and other places that use those bits.