Change the `K` normal mode overrides to use the example given in the
coc.nvim README file which uses Vim's builtin help when in `vim` or
`help` files, or checks if coc.nvim is ready and invokes
`CocActionAsync('doHover')`, otherwise fallback to using `keywordprg`.
Vim's :terminal feels much more ergonomic, adding various mappings to
make the experience more similar, mainly by adding a few `<C-w>`
mappings for the most common actions.
Additionally, disable vim-tmux-navigators default mappings and setup
both normal and terminal mode mappings for `<C-w>{h,j,k,l}` in addition
to the normal mode mappings for `<C-{h,j,j,l}>` to make the pane
switching experience more consistent across all buffer types.
Move logic to `autoload/tmux.vim` to detect the `vim` is being run
inside a `tmux` sessions and if the `set-clipboard` option is enabled.
This cleans up adding the optional `oscyank.vim` plugin when needed.
