Energy calculation logging statements

[urwahah]

for #68:

• added logging statements:
  • debug - print # hours where load is outside the AWHP operating limits
  • debug - added % cooling load covered by WWHP
  • debug - added % heating load covered by electric resistance
  • warning - if any equipment refrigerant charge or GWP is 0
  • warning - if there happens to be both HW boiler and electric resistance load
• revised sum functions in debug loggers to np.nansum() to avoid issues with measured datasets