Remove neons plugin.
Remove neons plugin.

Neons is no longer needed, remove neons plugin and HPDatabaseType.kNeons
and HPDatabaseType.kNeonsAndRadon. enum values kRadon and kNoDatabase
remain.

Further streamlining of radon access: parameter information was previously
fetched from many different plugins. Now it is centered to two places:
compiled_plugin_base::SetParams and luatool::SetParam. These two functions
fetch all necessary parameter id information etc from database, so it's no
longer necessary to re-fetch them later (like when writing file to disk).

fmidev/himan,fmidev/himan,fmidev/himan