No blank lines in inline interpreted roles:

```
% pandoc -f rst -t native
`no

blank`:myrole:
^D
[Para [Str "`no"]
,Para [Str "blank`:myrole:"]]
```

Backslash escape behaves properly in interpreted roles:

```
% pandoc -f rst -t native
`hi\ there`:sup:

`hi\ there`:code:
^D
[Para [Superscript [Str "hithere"]]
,Para [Code ("",[],[]) "hi\\ there"]]
```

Backtick followed by alphanumeric doesn't end the span:
```
% pandoc -f rst -t native
`hi`there`:myrole:
^D
[Para [Code ("",["interpreted-text"],[("role","myrole")]) "hi`there"]]
```

Newline is okay, as long as not blank:
```
% pandoc -f rst -t native
`hi
there`:myrole:
^D
[Para [Code ("",["interpreted-text"],[("role","myrole")]) "hi\nthere"]]
```

Use span for title-reference:
```
% pandoc -f rst -t native
`default`
^D
[Para [Span ("",["title-ref"],[]) [Str "default"]]]
```
