Updated the ATM90E32 library significantly

- 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