Use KisTagSP in signals in tagging widgets

This is a commit with a lot of changes. Most of them
are incomplete. It's a result of experimentation
in the middle of a huge rewrite and shouldn't be considered
complete or whole in any type of circumstances.
It does compile and shouldn't crash, the only
area that was changed is tagging.

Changes include:

• changing all QString& signals to KisTagSP (unless not

applicable, for example in case of the filter widget)

• commenting out a lot of code
• adding a lot of debug