removed code that was making all 32 bit registers positive
removed hard coded calibration angle values

- moved calibration variables to begin
- added destructor

- Removed calculation that would not allow some metering values to ever be negative
- Added function to calculate Power Offset values
- Tuned offset register values which will make metering values more accurate
- Calibrated phase angle for more accurate small current values

- Replaced lineGain with much more useful PGAGain, which increases the gain on current channels. Useful if using smaller CTs (1x) or larger CTs, like 200A (4x). The default is 2x
- Added config variable for line frequency. This allows the frequency setting to be switched in the front end software. Default is 60hz.
- Fixed GetActivePower, GetApparentPower, GetPowerFactor - all of these were not taking into account the lower 16 bit register, and were not outputting the correct numbers
- Fixed GetPowerFactor - the registers for power factor sometimes goes out of bounds for unknown reasons. Corrected this by doing a check on the output, and outputting 0 instead. Normally the value should be between -1 and 1.
- Fixed GetPhaseAngle - should have been unsigned short instead of signed. The output now outputs between 0 and 360
- Added classes for GetImportReactiveEnergy GetImportApparentEnergy, GetExportReactiveEnergy
- Added check for frequency lo and hi thresholds based on lineFreq
- Added check for voltage sag based on lineFreq, and adjustment based on lineFreq and ugain

For EmonCMS device setup - https://github.com/emoncms/device 
Upload to emoncms/Modules/device/data

This was done so calibration can be passed from the front end program without modifying the library.

Registers for ATM90E32 are a bit different from the ATM90E36.  The EMM Status Registers, SoftReset, and lack of start/checksums on other registers.