Line breaks in bold renders incorrect markdown

Bold generally should not be allowed to have line breaks in between them, or have whitespace on the inside, or they'll be treated as literal asterisks. So for example:

```
Our bold text

```

Results in:
```
**Our bold text\n **
```
Which will not render in bold with most markdown interpreters.

Instead we should move trailing line breaks outside of the asterisks:

```
**Our bold text**\n
```

and end and re-start bold for if it's not trailing, eg:

```
Our multiline
bold text
```
to
```
**Our multiline**\n **bold text**
```

- Version by 2016.9.19
- Python version 2.7.6