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.
Prior to this we were also performing highlighting inside HTML tags
which was wrong and causing weird behavior. Like, for example, if
someone added `emoji` as an alert word then any message containing
both emoji and alert word was rendered with a jumbo emoji.
Fixes: #4357.
We remove the `page_params.alert_words` since `alert_words.words`
is the sole source of alert words. Use of `page_params.alert_words`
could lead to bugs when alert words are updated since it is not updated.
Previously, we were checking if a particular user was the current user
in dozens of places in the codebase, and correct case-insensitive
checks were not used consistently, leading to bugs like #502.
Anders Kaseorg
Tim Abbott
Armaan Ahluwalia
Steve Howell
Harshit Bansal
Steve Howell
Rafid Aslam
AZtheAsian
Tommy Ip
Tim Abbott
Leo Franchi
Luke Faraone
Steve Howell