support Python in routes

[terrablue]

Initial concept / support in 251a5bb.

• [x] trydepend on pyodide
• [x] handlers (minimum: view, redirect)
• [x] request.body
• [x] dispatchers (request.{path,query,cookies,headers}
• [x] request.session
• [x] request.store.* (async)
• [x] documentation: extend /modules/binding and create /modules/python