Fennel updates, macro and seed.sh improvements

Hey there! Quite a lot went into this release and it too longer than I expected because there were some Fennel things to get fixed before it went out for general release (bakpakin/Fennel#331).

Without further ado, here's the full changelist!

• Updates to the seed.sh script to provide some slightly nicer output and renaming of files on your behalf. Thanks @tami5 for the PR (#14)!
• Return values from fn-bridge by default, it was confusing not having this as the default. Now you can opt out of returning the value from a bridge-fn rather than opting in.
• Update to Fennel 0.6.0 + a few extra commits to fix a few things. This is more like 0.6.1-alpha. Hopefully some more subtle bugs fixes and improvements have slid in!
• Ensure a bad require doesn't kill the module. Before, if you tried to require something that didn't exist you'd get a horrible large error and then that module was unusable until you either cleaned it up yourself or restarted Neovim. You can now "unrequire" modules by deleting them from the definition and a module will survive a bad module require.
• Add *module* and *module-name* as locals you can access in your module source code. This allows you to inspect your actual module table as well as the name of the module you're currently evaluating within. This can be useful for referring to the current namespace from VimL function bridges.
• Ignore paths that end with macros.fnl in glob compiling, this means you can create macros.fnl files in your dotfiles and plugins without having Aniseed attempt to compile them to Lua (that's not possible). This should make it easier to use macros in your projects!

And that's all! There were a bunch more commits but I think this is all of the highlights, I hope you find these changes useful and I hope I can bring you more soon. Have a great weekend!