Add antifennel support to aniseed

[randomizedthinking]

This is a simple write-up to add antifennel support in aniseed.

• the antifennel source code is added under the lua/deps directory;
• no any other dependence is added to aniseed;
• one keymap is added to lua file: to show antifennel source code;
• one keymap is added to fennel file: to show compiled lua code;

[Olical]

So Aniseed doesn't have ANY mappings yet and that's by design, as soon as you add mappings you need to add user configuration and more layers of documentation because I can promise there will be people instantly asking "WHY this mapping, I want X not Y!" - I've learned through my Conjure development that I should never assume a default I think is fine will be okay for everyone. There will ALWAYS be someone who doesn't like it and wants to change it.

I am still potentially okay with antifennel being included in the project but I think we should hide it behind a command like AniseedAntiFennelFile or something akin to the existing AniseedEval and AniseedEvalFile commands. The user can then create their own mappings to call those if they so wish.

The key thing should be exposing Lua functions that can be called by other pieces of software. Either user code OR Conjure which I treat as the interface to Aniseed's tooling. I don't want to reinvent the pop up windows and their 10s - 100s of config options that come along with it.

I think we should make the Aniseed side headless, merge it soon behind a command, then add a mapping into the Conjure Aniseed client that prints things into the log / HUD. That way I don't have to maintain two sets of config, mapping and UI systems.

[randomizedthinking]

Sounds good. I will retract this PR and then submit a new one. Basically, as you advised, the two key mappings will be converted to two commands. Thanks.