Follow up of commit 2a1305d. Replace all local variables named 'msgid'
with 'message_id' in all JS and HTML files, and adds a linter rule for
it as well.
Resolves#12952.
We do this because now we send a message to stream if a reminder
is set and won't need the notification above the compose box saying
that we set a reminder. We would still need that notifications for
the send later feature so we make the construct conditional.
This commit prepares the frontend code to be consumed by webpack.
It is a hack: In theory, modules should be declaring and importing the
modules they depend on and the globals they expose directly.
However, that requires significant per-module work, which we don't
really want to block moving our toolchain to webpack on.
So we expose the modules by setting window.varName = varName; as
needed in the js files.
Vinit Singh
Aditya Bansal
Steve Howell
Joshua Pan
Armaan Ahluwalia
Shubham Dhama