Export startCompletionEffect and closeCompletionEffect

[ankoh]

This commit is exposing startCompletionEffect and closeCompletionEffect.
It allows us to modify StateFields whenever the completion popup opens/closes.

[ankoh]

Let me know if there's a better way to update StateFields whenever the completion is either applied or aborted.
I thought about hooking into Candidate apply, CompletionResult validFor and CompletionResult map, but you're still missing some cases where the completion is, for example, canceled by deleting the whole word.

[ankoh]

Ah, I just found that mine is a duplicate of #24 , sorry.

[ankoh]

Feel free to close if you don't like exposing the effect, I'll use the workaround of #24 in the meantime.

[marijnh]

Yeah these are really intended to be internal.