BRANCH 4.4: more work on the single asset view and pipeline editor
(mostly colors and exposed columns)
BRANCH 4.4: support for "extra" header in table layout.  It is not quite
clear when this can be set, but it prevents cut off when the last column
is floating left (ie floats and integers)
BRANCH 4.4: hid python triggers from non-admin users
- drag and drop on tile and table layouts