talkatu/talkatu

Implement the TalkatuMessage interface with TalkatuInput, delete TalkatuDemoMessage, and change TalkatuAttachment's id from gint64 to guint64
# h1
## h2
### h3
#### h4
##### h5
###### h6
plain *emphasis* _emphasis_ ~~**strong**~~ __strong__ `code` plain
[Test link](https://pidgin.im)
`code`
```
code?
```