README: update install-from-source instructions to use tarball

README: fix grammar

tallyard.xyz: revamp Contributing and Future Work sections with lists

Remove TODO.org

These have all been migrated to the new issue tracker:

https://todo.hnitbjorg.xyz/~edwargix/tallyard/1
https://todo.hnitbjorg.xyz/~edwargix/tallyard/2
https://todo.hnitbjorg.xyz/~edwargix/tallyard/3
https://todo.hnitbjorg.xyz/~edwargix/tallyard/4
https://todo.hnitbjorg.xyz/~edwargix/tallyard/5
https://todo.hnitbjorg.xyz/~edwargix/tallyard/6
https://todo.hnitbjorg.xyz/~edwargix/tallyard/7
https://todo.hnitbjorg.xyz/~edwargix/tallyard/8

tallyard.xyz: remove link to presentation in navigation links

It's mentioned a few paragraphs down.

tallyard.xyz: add links to mailing list and issue tracker

tallyard.xyz: use symbolic Matrix room link

This seems to work better on mobile and probably will make room upgrading much
easier, should we ever need to do that.

Set Matrix device display name to something reasonable

We don't need this return value to be named

Remove useless comment

I accidentally copied this.

Delete old Nonce implementation

This was left over from the libp2p implementation.

Bump dependencies

Fix clone URL in README

Add note in README on git-send-email.io

Fix test failure for Println

Add README section for contributing

Update go-import and go-source meta tags on tallyard.xyz

Update repo and presentation links on tallyard.xyz

Update README

Don't process an event when it's already being processed

Set larger limit for filter