Add <Plug>(neosnippet_foo) to expand/jump in n/xmap

[aileot]

This PR will let users to map them easier.

I only use <Plug>(neosnippet_expand_or_jump) so I've not check the others work. I'm sorry for the irresponsibility.

[Shougo]

Why the PR is needed?? Please describe it more clearly with examples.

And please update the documentation.

[aileot]

This PR is for easier configuration for users; small differences between similar texts often confuse us in a feature review, and drive us to search through documentations even when we are not naive in the field.

Sometimes we leave Insert Mode while a snippet's unfinished. In such a case, I often want to jump and restart to replace the next place-holder in the snippet. I believe some other users do, too.

Without this commit, we should write a script like below to enable such a motion within a key lke <C-\>

imap <C-\> <Plug>(neosnippet_expand_or_jump)
smap <C-\> <Plug>(neosnippet_expand_or_jump)

nmap <C-\> <c-g>h<Plug>(neosnippet_expand_or_jump)
xmap <C-\> <c-g><Plug>(neosnippet_expand_or_jump)

This lacks parity. But with this commit, we can configure like below.

nmap <C-\> <Plug>(neosnippet_expand_or_jump)
imap <C-\> <Plug>(neosnippet_expand_or_jump)
vmap <C-\> <Plug>(neosnippet_expand_or_jump)

" or with no care to `:omap`; however, it fails to remove any place-holder though it can jump anyway. Do you see the reason?
map  <C-\> <Plug>(neosnippet_expand_or_jump)
imap <C-\> <Plug>(neosnippet_expand_or_jump)

Don't you feel it easier with this example rather than the former?

Of course, I'll update the documentation as long as you make sure to accept this PR.

[Shougo]

Hm. OK. I accept the PR. Please update the documentation.

[aileot]

OK. I will.

By the way, would you explain the difference between <Plug>(neosnippet_expand_or_jump) and <Plug>(neosnippet_jump_or_expand) here.

There seems no explanation about it in the help, and I only use <Plug>(neosnippet_expand_or_jump) as I said above.

If you write it in this thread, I will paste it in my fork and make a commit. It would be bothersome to merge/rebase and so on.

[Shougo]

expand_or_jump means check expand before jump. jump_or_expand means check jump before expand.

[aileot]

OK. It was a matter of the priority after all. I will mention to it in the documentation, too.

[aileot]

I've updated the documentation.

May I replace <Plug>(...expand_or_jump) with <Plug>(...jump_or_expand) in the examples of the documentation? I recently found unexpected expansions sometimes happen while editing a snippet.

In my consideration, it is more complex usage to expand rather than to jump, and documentation should be written close to naive users who expect simpler usage.

[Shougo]

In my consideration, it is more complex usage to expand rather than to jump, and documentation should be written close to naive users who expect simpler usage.

You can improve the documentation later.