Change database to allow sub-categories

Also add a field to mark default sub-category
Categories: add new category
Show only root categories in admin
List categories and sub-categories
Edit category
Delete sub categories
Remove subcategory when adding a category
Delete a root category
Delete sub-category with multiple category for items
Delete category with multiple category for pins
pin loader: save to multiple categories
pin loaders: show pins with all its categories
Pin loaders: Show selected categories editing pin
Pin loaders: edit categories
Pin loaders: delete pin with multiple categories
Pin loaders: update categories with image upload edit
Select cool items with multiple categories
Registration: select categories with multi-categories
Fix categories in profile listing
show pin with multiple categories