Initial commit of historical leaf temp/par averaging approach.

[drnimbusrain]

@MaggieMarvin This is a first crack at explicitly calculating historical leaf temp and par values used in canopy-app. I have created a new option, "hist_opt" to turn this on (hist_opt=1). See the description in the README, but if the canopy-app simulation is < 24 hours then instantaneous values will still be used, and if turned on and run > 24 hours, historical running avearges can be used. Can you closely test this using a longer simulation and analyzing the output after 24 hours against MEGAN and PECORINO?

This is currently a draft and needs thorough testing:

• [x] Compare spatial impacts of historical averaging against MEGANv2 and MEGANv3
• [x] Test historical approach for > 24 hours for assessing the e-folding running averages
• [x] Test historical + gamma_sm impacts.

[drnimbusrain]

@MaggieMarvin I have merged develop (with gamma_sm changes) into historical for your testing of both options on and running it longer to test the running average feature when > 24 hours.