Add strip_url_static_file_prefix to filters
Add strip_url_static_file to base sphinx template and templateexporter.py
Add tests for filter
`strip_files_prefix` now also strips markdown style links, `latex_base` updated to include filter
transparent background match ... all colors
allow to load config from json file

json takes highest precedence and is loaded last
fix plural and embeded
allow ipython console to handle text/plain display
test for text/plain display handling in console
refactor starting and stopping pexpect
removed unused imports
don't double display in the console

hand_rich_data was also used by pyout, refactored so we don't display it
twice.
survive failure to bind to localhost in zmq.iostream

subprocess output will be unavailable, but the process will not die.
Don't build Python modules unnecessarily before symlinking to site-packages
Only ignore existing target for symlink if it is already a symlink
don't do anything if add_anchor fails
use if main block in entry points

closes #4698
Delete an old dictionary available for selecting the aligment of text.
Deleting the counterpart of the dict in the templates.
Making reveal font-size a relative unit.