add search feature

[maidis]

It may not be very important to have a search feature in a pastebin service, but there are some services that have this feature and I think it's really cool.

You can let me know if there's anything to fix or if it will be easier for you, you can do it yourself too because I'm quite a beginner.

Search button and search page based on:

• https://github.com/cutelyst/applyst/blob/13e7e7d9b0fc6e780aab2328fc40a3b411b21399/root/src/search.html
• https://github.com/cutelyst/applyst/blob/13e7e7d9b0fc6e780aab2328fc40a3b411b21399/root/src/base.html

and search method based on all method:

• https://github.com/cutelyst/pastelyst/blob/master/src/root.cpp#L233

[dantti]

This looks fine, however I think using FTS5 would be nicer: https://sqlite.org/fts5.html Not sure how much overhead that would bring, but I guess it's not much