Interpret escape sequences in KEY=VALUE pairs as literal strings.

Hey,

I was looking to sort the output of dconf and this was the 1st hit on Google to my query. Found an issue on my 1st test run.

Example:
We want:
```
[org/mate/pluma]
history-search-for=['aaaa\nbbbb\tcccc\ndddd\neee']
```

We got:
```
[org/mate/pluma]
history-search-for=['aaaa
bbbb	cccc
dddd
eee']
```
Other than that it does the job perfectly.