Break diameterCalculator markup out into a partial
Make diameterCalculator instantiable constructor

the diameterCalculator module exports a python-style constructor function that returns a new instance of the diameterCalculator. Useful for having multiple instances per page, as in the map page.
Add diamCalc to quick edit and add tree forms

fixes #500 on github
Remove outdated docs
Hide multiple trunks in 'add tree' mode
Merge pull request #535 from steventlamb/bug/500_diameter_calculator

Bug/500 diameter calculator