Improve error handling in parameteric remote

[bengtmartensson]

1. Should not just ignore signal without parameters but with a name
2. Handling of signals with missing parameters:
   • Girr: now exports non-render able signal, without checking
   • Other: throws ugly exception
   • Better error messages: should point to exactly what signal is flawed.

Optional: by missing parameters, list all that are missing, not just the first missing.

[bengtmartensson]

1. Should not just ignore signal without parameters but with a name

This was fixed in #511.