Drop dead code from ListView.

I have really no clue where this chunk originated from and can not make
neither heads nor tails out of it's original purpose. Therefore I
dropped it as it was always skipped.
Refactor the DCGE constants for the correct ones from ModelInterface.
Bugfix for checkbox sub palettes - they were detected as selects in certain cases.

When a checkbox was named with an underscore it was incorrectly detected
as select box with an empty value.