Implement front end to LJ::Support::define_cat

- Consolidates changes to table supportcat.

- Adds new priv.

- Basic form content and processing.

Fixes #965
Changes for request following review

Fixes #965
Second round of review comments

Fixes #965
Merge pull request #1022 from pauamma/bug-965-supportcat-creation-frontend

Implement front end to LJ::Support::define_cat