feat!: allow running multiple kanata instances concurrently

[rszyma]

Closes #10

TODO:

• update README.md

[rszyma]

I noticed that the presets in tray menu are being displayed in random order after being read from config file. It's happening because we parse presets into golang's map, which doesn't support preservation of order of insertions.

To fix this a wrapper for map like this one would need to be used, however the toml parsing library we currently use have no support for parsing complex types into custom structs.

Edit: pelletier/go-toml has a unstable api workaround to get order of mappings

[rszyma]

• Only general.allow_concurrent_presets is left to be implemented now I think?

Also:

• disable "Open Logs" button when no previous log is available