User search for streams will now return results where the stream
description (but not the stream name) include the string in the
user query.
The filtering process first obtains the streams whose names match the
user search query, then sorts and displays them. From the remaining
streams, it obtains streams whose description matches the query and
displays them in sorted order after the name match results. Other
streams are not displayed.
Fixes: #2674.
When filtering streams, we were incorrectly treating the regexp input
provided by the user as a regular expression, meaning that terms like
`c++` would trigger errors because they are invalid regular expression
syntax. We fix this by replacing RegExp with a simple IndexOf check.
Node test added by tabbott.
Fixes#3559.