Tracking of livecode execution is made possible by making the page
context with course, batch and lesson available in js.
Added a global page_context variable in js and the data for that gets
initialzied in the learn.py.
- added PageExtension plugin to inject custom styles scripts in a page
- removed the livecode integration and enabled PageExtension plugins for
learn page
- also merged the profile_tab.py with plugins.py
- added a utility to find the macros from given text
- updated the before_save of lesson to find exercises using the macros
and update the exercises as before
Issue #115
