Add search functionality and hotkey

[glensc]

Coming from vim, I really missing search functionality:

• search for commit id
• search for commit message

I would expect this to be activated like in vim: / hotkey and behave like hlsearch enabled

If I'm reading screenful of commits (don't ask why), I find my fingers type faster to find commit I'm interested in by search than visual grep (👀) for the commit

[MitMaro]

I really like this idea and I wish I had thought of it myself!

[MitMaro]

Search from within the list view was added in #797. I haven't added screenshots to the README yet, but in development, / starts a search, Enter "finishes" the search, then n and N move between search results.

I tried to keep the default key-bindings and behaviour similar to vim.

I've been working on this for so long, that I forgot there was an issue open for it. 😅

I'm hoping to do a release early in the new year, that will contain this functionality.