Support term substitutions (like "Resource" -> "Watershed Solution")

* Global context gets `term` dictionary with text substitutions
* Reference using the desired term variant (title/lower case; singular/plural), e.g. `term.Resource`, `term.Resources`, `term.resource`, term.`resources`
* Current substituable terms are "Resource" and "Resources" (but we can add more if we want)
* Replace all uses of e.g. "Watershed Solution" with e.g. `{{ term.Resource }}`

Also 	add a comma between plot count and resource count on map page.