Rack, Roda, Sinatra and other framework compatibility (when running on Opal and Node or alternative)

[janbiedermann]

... currently is lacking.

These patch sets show where things are missing in opal, or things go wrong:

For Roda:
jeremyevans/roda@master...janbiedermann:roda:master

For Rack
janbiedermann/rack@1dadea0

For Sinatra, Rack-Protection:
sinatra/sinatra@main...janbiedermann:sinatra:main

For Mustermann:
sinatra/mustermann@main...janbiedermann:mustermann:main

For Rack-Session:
rack/rack-session@main...janbiedermann:rack-session:main

(Issue here to be referred by PRs which fix things)