Regex searching needs to work across all types

[mattpass]

Regex searching was added but needs a lot of testing and working with multiple results.

Look at this commit, changes made and the TODOs within it: 01df964 but first TODO should be covered via this commit: 0fb0644

Also needs bracket pair balacing code to not consider it regex unless bracket pairs match. Perhaps could also highlight in red if regex filter on and a bracket (or general regex format) issue?

[mattpass]

Regex searching is being finalised at the moment, to work with multiple results.

TODO item in JS covered and TODOs in multiple-results.php being covered as part of regex search finalisation.

Have added bracket pair balancing checks and other checks, with find input box turning red when invalid.