The following are the changes being introduced in this commit:
1. Instead of mapping the query language to various query params on the
client side, we've decided that the benefits of having a more robust
query language far outweighs the benefits of having a more human readable query params in the URL.
As such, the `/filter` route will just accept a single `q` query param
and the query string will be parsed on the server side.
1. On the `/filter` route, the tags filtering query language is now
supported in the input per the example provided below:
```
tags:bug+feature tagged both bug and feature
tags:bug,feature tagged either bug or feature
-tags:bug+feature excluding topics tagged bug and feature
-tags:bug,feature excluding topics tagged bug or feature
```
The `tags` filter can also be specified multiple
times in the query string like so `tags:bug tags:feature` which will
filter topics that contain both the `bug` tag and `feature` tag. More
complex query like `tags:bug+feature -tags:experimental` will also work.