Allow to make keywords case insensitve again

[Nudin]

In previous versions the keywords used to be case-insensitive. But now they aren't anymore. I struggle to get used to this change. So here is a PR to allow case-insensitive keywords search again.

First commit makes them always case-insenstive, but I can also see why people might like them case sensitive I then added an option to let the user choose.

[jobisoft]

Not sure why case-insensitive keywords are needed. As far as I could see it, it was a bug in older versions. Why not change the keyword they way you want it?

[Nudin]

Not sure why case-insensitive keywords are needed. As far as I could see it, it was a bug in older versions. Why not change the keyword they way you want it?

No matter how often I use it, I never remember which case I got for some of the keywords and always get it wrong on the first try. (Also when typing fast I sometimes mistype the casing and let the spell checker correct it in normal text)

[jobisoft]

Oh, ok, that does seem like a good reason. I will look at this. Not sure if I will use this PR or a different approach, but I will consider adding an option to make keywords case-insensitive.