Sort skin tone emojis last
### Problem to solve
When entering for example the very common `:thumbsup:` emoji, one has to type at least `:thumbsu` because all 5 autocomplete slots are occupied by the various skin tones of the thumbs-up emoji.

### Proposal
Sort the skin tone emojis at the end, so the order becomes:
```
thumbsdown
thumbsup
...
thumbsdown_tone1
...
thumbsdown_tone5
thumbsup_tone1
thumbsup_tone2
...
```
This way you can first choose the emoji (e.g. `thumbsup`) using autocomplete and then you can still add the desired skin tone *to that particular emoji* simply by hitting backspace.
issue