HTML should not be i18ned
Merge pull request #6393 from edx/remove-useless-gettext

HTML should not be i18ned
Add 'h' to edxmako’s default filters

This enables HTML encoding by default.
Apply 'n' filter when data shouldn’t be HTML encoded

Also apply 'escapejs' filter on top of json.dumps.
Remove unneeded 'h' filters from templates
Replace HTML entities with real characters

Translations will have to be updated.
Let template mechanism escape HTML
Escape underscorejs templates

Use <%- … %> instead of <%= %> to render text.
Fix course index titles encoding
Encode section name in welcome back message
Escape graph labels in courseware progress
Update tests according to templating changes
Update capa tests

Apply the same template modifiers as in edxmako.
Update test templates to add `| n` modifier, when necessary.
Compare unicode strings in course about tests
Replace &hellip; with … in JS code

There should not be any HTML in translation strings.
Remove &amp; from checklist buttons

Unfortunately, this doesn’t fix existing courses since checklists
buttons’ labels are stored in the modulestore.
Remove all ellipses
A better way to make all translation strings plain text.

By making _() return an escaped Markup object, we can mark HTML chunks
with HTML(), and have logical .format() semantics without a specialized
and too-narrow helper like format_html.
Convert lots of translation strings to the new way to do plain-text translation strings
More messages converted