Ignore function attribute deferred
UTF8 fallback for encode/decode with no connection

- Add qWarning message when encoding/decoding before the connection
  is established
- Fallback to utf8
fixup encode/decode
Pass neovim ::spawn() parameters at the begining

- When spawning Neovim with command line parameters, pass the given
  parameters first, and --embed at the end
Initial support for the abstract UI

- New class Shell exposes a GUI for Neovim
- New binary nvim-qt to start a GUI
* There are still issues that need fixing: keyboard input and
  resize