Possiblity to check sanity of parametric remote

[bengtmartensson]

In particular, check that

• protocol/parameters make sense, in particular
  • protocol names are known and renderable,
  • all necessary parameters assigned,
  • no unnecessary parameters used
• the same signal (= parameter values) is not present several times
• names conform to some (user selectable!) scheme, e.g. Lirc/Linux input event names, C identifiers,... (#145)
• the names are unique
• If T is assigned, issue a warning (this is seldomly sensible).

The check may be invoked

• on request, e.g. from pull-down menu,
• before export; if failed, should perform a "proceed anyhow?" inquiry,
• automatically, on import(?)

[bengtmartensson]

Better to do this in the context of general overhaul of the remote editor.