Pin eco.py requirement to fix tests
Don't hide/cancel tree counts with ecobenefits

fixes #813 on github.

A previous commit, 99c236aad3965e0dac1b601ca1b70fd59b451684, removed ecobenefits for cases where the instance does not overlap an itree region. This incorrectly disabled tree counts along with it. This commit re-enables tree counts.
Add explanation text when eco turned off

fixes #799 on github.