Co-Authored-By: Kyle Caverly <kyle@zed.dev>

This is a deep cut. There's still more work to do until we start
building UI with this. I've approached this as additively as possible,
but I've made a few changes to the rest of the code that I think would
be good to upstream before proceeding too much further.

Most of the interesting pieces are in gpui/playground, which is a
standalone binary that opens a single window and renders a new kind of
element. The layout of these new elements is provided by the taffy
layout engine crate, which conforms to web conventions. The idea is that
playground is relatively cheap to build and work on. As concepts
coalesce in playground, we can drop them into gpui and start
transitioning.

A complete overhaul of the way vim did paste. This ended up being more
involved than I expected because of the variety of different behaviors
that vim exhibits when copying/pasting between various modes.

Release Notes:

- vim: support P for paste before
([#1869](https://github.com/zed-industries/community/issues/1869)).
- vim: support P in visual modes for paste without overriding clipboard
- vim: fix position when using `p` on text copied outside zed
([#469](https://github.com/zed-industries/community/issues/469)).
- vim: fix indentation when using `p` on text copied from zed
([#1015](https://github.com/zed-industries/community/issues/1015)).
- all: Separate copied multi-selections by `\n`

Release Notes:

- vim: Fix escape to dismiss suggestions in insert mode.

Co-Authored-By: Julia <30666851+ForLoveOfCats@users.noreply.github.com>

- vim: support P for paste before
- vim: support P in visual mode for paste without overriding clipboard
- vim: fix position when using `p` on text copied outside zed
- vim: fix indentation when using `p` on text copied from zed

Add `$` and `#` and a smoke test for vim-mode respecting the
configuration.

Co-Authored-By: Antonio Scandurra <antonio@zed.dev>

Co-authored-by: Conrad Irwin <conrad.irwin@gmail.com>

Release Notes:

- Added default key bindings for `NewFile` and `NewDirectory` in the
project panel (bound to `cmd-n` and `alt-cmd-n`, respectively).

This PR adds new config option to language config called
`word_boundaries` that controls which characters should be recognised as
word boundary for a given language. This will improve our UX for
languages such as PHP and Tailwind.

Release Notes:

- Improved completions for PHP
[#1820](https://github.com/zed-industries/community/issues/1820)

---------

Co-authored-by: Julia Risley <julia@zed.dev>

This PR adds new config option to language config called
`word_boundaries` that controls which characters should be recognised as
word boundary for a given language. This will improve our UX for
languages such as PHP and Tailwind.

Release Notes:

- Improved completions for PHP
[#1820](https://github.com/zed-industries/community/issues/1820)

---------

Co-authored-by: Julia Risley <julia@zed.dev>

[This PR has been sitting around for a
bit](https://github.com/zed-industries/zed/pull/2845). I received a bit
of mixed opinions from the team on how this setting should work, if it
should use the full model names or some simpler form of it, etc. I went
ahead and made the decision to do the following:

- Use the full model names in settings - ex: `gpt-4-0613`
- Default to `gpt-4-0613` when no setting is present
- Save the full model names in the conversation history files (this is
how it was prior) - ex: `gpt-4-0613`
- Display the shortened model names in the assistant - ex: `gpt-4`
- Not worry about adding an option to add custom models (can add in a
follow-up PR)
- Not query what models are available to the user via their api key (can
add in a follow-up PR)

Release Notes:

- Added a `default_open_ai_model` setting for the assistant (defaults to
`gpt-4-0613`).

---------

Co-authored-by: Mikayla <mikayla@zed.dev>

This reverts commit 046759a366a3ed65ae3c0deacbd880ffbfe291f9.