Fix issues related to multireddits misbehaving

RES fails to handle multireddits correctly in at least two ways:

1. The hot/new/rising/etc tabs on a multireddit link to an incorrect
location if the multireddit is owned by a user other than the logged-in
user.
2. The commandline commands for switching to a different tab (`./t`,
`./c`, etc.) take you to an incorrect location if used on a multireddit
(owned by any user).

This commit addresses both those issues. The fix in utils.js is kind of
a kludge, but I don't want to risk breaking the `match` regex in
`RESUtils.currentUserProfile()`.
Add sort-by-gilded/promoted to commandline

In addition to the existing `/n`, `/t`, `/h`, and `/c` sort modes
already available from the RES commandline, this commit adds support for
`/g` (gilded) and `/p` (promoted/ads).

Note that you cannot view "promoted" content by a single user, and that
"sorting" by gilded for a single user is a bit different than sorting by
new/top/etc, so there is a bit of special handling for those cases.
Merge branch 'master' of https://github.com/honestbleeps/Reddit-Enhancement-Suite
Use RESUtils.profileRegex instead of a kludge

`RESUtils.profileRegex` seems to correctly identify multireddits as
non-user-profile pages, so we may as well use that rather than doing a
check for whether we're in a multireddit first.

`.currentUserProfile` was the only one of the four `.current*` functions
to have a regex hardcoded inside the function anyway, so this works out
well for future maintainability.
Merge remote-tracking branch 'upstream/master'
Merge branch 'master' into multireddit-bugs
Merge pull request #1722 from ashvinsrivatsa/multireddit-bugs

Fix issues related to multireddits misbehaving