FEDX-93

These are developer only pages, so can not be seen in production
environment. On devstack, you can access these pages in LMS and
Studio at:

    /template/ux/reference/pattern-library-test.html

FEDX-105

TNL-4160

TNL-4160

Make base.html Mako template safe by default by:
1. Add page-level default of html escaping
2. Fix escaping of all variables in base.html
3. Fix escaping of all dependent underscore templates
Also includes additional best practices for certificates and
textbooks JavaScript/Underscore in order to complete that work.

TNL-3425

TNL-4106

- Rename escape_json_dumps to dump_js_escaped_json
- Rename escape_js_string to js_escaped_string
- Update js_escaped_string to output empty string for None
- Introduce dump_html_escaped_json
- Move dump_js_escaped_json after the pipe as new best practice
- Introduce additional uses of helpers
- Introduce new djangolib directory and move js_utils

- Remove escaping in display_name_with_default
- Move escaped version to deprecated display_name_with_default_escaped
- Does not include any other changes to remove double-escaping

Thanks to agaylard who initiated this work:
https://github.com/edx/edx-platform/pull/10756

TNL-3425

Please note that this is a squshed commit and the work of:
Symbolist, macdiesel, nedbat, doctoryes, muzaffaryousaf and muhammad-ammar

Make escaping for json simpler and more consistent in Mako templates
- add escape_json_dumps to escape and json.dumps
- add escape_js_str to escape javascript string
- refactor Studio to use escape_json_dumps in Mako templates

TNL-2646: Escape json.dumps

May improve performance.
TNL-3538

ECOM-2443

TNL-2695

TNL-2487

The old code would compute the language direction once when the template
was loaded.

TNL-2269

* to reflect support for IE10 and above
* to only flag IE9 (for emergency's sake) with specific html class attrs

* to reflect support for IE10 and above
* to only flag IE9 (for emergency's sake) with specific html class attrs
* to remove HTML5 shiv that's not needed for IE10 and above

This reverts commit b8184d18.

[second attempt which addresses bug building Studio]

This reverts commit 1d6fceda.

Respond to review comments:

- Rename build and config files for consistency between lms/studio.
- Fix merge conflicts with lms require config.
- Devstack uses optimized pipeline to skip require JS optimizer step
- Add tests for render_require_js_path_overrides

SOL-1, SOL-2, SOL-3

For theming and internationalization

* removing unused font-family-centric Sass variables
* removing unused graphic images and Sass references
* clean up of style removal fallout