Tabs order

In tabs mode (and when the query is empty) order tabs by recency, so the previous tab is just one `Enter` away.

Fixes #1146 (well, indirectly).
Took me a moment to realise what this actually meant. For clarity, can we say
```
if suggestion.queryTerms == ""
```
or maybe
```
if suggestion.queryTerms.length == 0
```