Allow using dispatch for tag creation

[kirstein]

Generating tags on a large project takes time. Thats especially annoying when generating tags on each save since system execute is synchronous.

The solution here is to use vim-dispatch, which allows us to trigger long tasks in async wrappers (tmux, screen, etc).

Added g:CoffeeAutoTagUseDispatch variable that dictates weather we should try to execute coffeetags with dispatch or not.

A bad demo:

[lukaszkorecki]

hi @kirstein - looking good, can you update the README with a section explaining vim-dispatch integration?

[kirstein]

Hey! Sorry about the delay. I now have added a small writeup to README. Let me know if you need something else to be done.

[lukaszkorecki]

@kirstein Magic ✨

Gonna merge and make a release later today