Unpollute JavaScript global namespace

As these variables were being assigned without being explicitly
declared, they were implicitly added to the global namespace.

This commit removes 59 variables from the global namespace.
Remove superfluous whitespace and comments
Avoid use of Array/Object constructors

Array and Object constructors, as opposed to their literal values ('[]'
and '{}'), incur additional overhead and are less effectively optimized
by the compiler.
Update to latest XBlock
Fix check and show answer for split
LMS-11237
Updating the footer for edx.org and open edx.

Move the open edx logo inside the div

Adding a bunch of placeholder views.

indenting.

Making some styles work against LMS sass.

Adding back the old edx footer and associated icons, with a feature flag.
Merge pull request #4745 from stvstnfrd/circuit/clean

Remove JavaScript variables from global namespace
Update activation email text

Make it more active.  Adds a separate section for edX.org-specific copy,
because it's hard to make it generic.

LMS-11084
Merge pull request #4952 from edx/pmitros/latest-xblock

Update to latest XBlock
Merge pull request #4855 from edx/sanchez/update-platform-footer

Updating the footer for edx.org and open edx.
Merge pull request #4931 from edx/reruns/check_answer

Fix check and show answer for split
Merge pull request #4325 from edx/victor/update-activation-email-text

Update activation email text
Update opaque-keys library to use block_id for html_id for new keys.
Catch more places where get_children was giving us version aware references.
LMS-11237