Blender Git Loki

* The filter function submitted to template_ID can override dot prefix hiding of names by returning true for such a name. This will be used to allow hiding of image icons in other menus while still showing them in the brush icon roll out.

* I have everything set up to only show names that begin with .imageicon., however I have not hooked it up in the UI because I believe that the open function for icons should automatically rename the image id blocks by prefixing them with .imageicon. and doing so will require a lot more work.
For that reason I'm going to leave this as is for now, also there may be a better solution.