Alias `T` to `TComment` instead of using a cabbrev.

The abbreviation would mess up commands with "t" in them, like turning
`tjump` into `TCommentjump`.

Replace the abbreviation with a new `T` command that acts as an alias
for `TComment`. I didn't include argument completion because I don't use
that. Otherwise, replicate the `TComment` command's definition and pass
all parameters to it. This gives us a short alias for commenting, and
`T` is the first completion with `:t<Tab>`.

I used to be able to type:

    :59-63T<Tab><Enter>

to comment out a block. Now, since `TBuffer` is earlier alphabetically
than `TComment`, the above no longer works.

Add two command line abbreviations to make it easier to use these two
commands.

Use `s` to wrap text in a GitHub suggestion.

Before:

    Text

After:

    ``` suggestion
    Text
    ```

I kept getting E211 errors when switching Git branches with
added/missing files or E321 errors. Normally, I'd get the error once,
dismiss it, and be done with it, but on a new machine with a recent Vim
install, the errors kept coming back up every few seconds,
insupportable.

Unless I can think of something better, take a heavy-handed approach and
disable this on new Vims.

Add a plugin for a custom tabline. Still a lot of room for improvement
here, but I really wanted something that would tell me the tab numbers
to make it easier for me to switch between tabs using #gt.

Made a mistake. Using `yi` means that commands like `yi(` don't work
anymore so change the mapping to `yoi` because I can't think of anything
better.

I often find that I want to delete the line inserted from the `yo`
mapping. This adds a mapping that doesn't add the line in the first
place so I don't have to go back and delete it after pasting.

Make a plugin out of a Stack Overflow post for a better autoread
augroup.

The `autoread` setting in vim will automatically reload a file if it's
been changed outside of vim (if you've made unsaved changes vim will
prompt before loading the file). By default, however, vim doesn't
automatically detect when a file has changed. It only happens when you
do certain things. This sets up an autocmd to force a check a bit more
often by tying into the CursorHold events. A bit hackish it seems but it
works like a charm.

This has been sorely needed especially since yesterday when I was
switching git branches in a project several times and editing various
files only to be alerted upon saving that the file on disk has changed.
Previously I would say it was a minor annoyance to have to type :e! in
those situations. Yesterday it was a freaking pain in the glaiven since
it happened unexpectedly so many times and after I was ready to
commit/save edits.

Copy of Tim Pope's paste helper. I didn't want the full unimpaired.vim
but this functionality is really useful, so including it here in a
separate plugin.