Intelligently fill table cells

• Added Insert Breadcrumb command to add a breadcrumb at the top of a page showing its hierarchy in the notebook
• Added Select All Images command to allow action on all images on a page, for example to quickly delete all images
• Added Copy Across, Copy Down, Fill Across, and Fill Down commands to intelligently fill subsequent cells in a table, see Wiki for details
• Fixed Image Resize command to properly resize image storage size with preset width values, per #269