Make code completion more smart on case sensitivity about moonshine-feathersui-text-editor

[joshtynjala]

@piotrzarzycki21 I just implemented a new weighting algorithm to filter and sort completion items. It's still simpler than what you asked for, but it should be a noticeable improvement. ce will match createElement now. However, crEate will match it too, because the new algorithm is still case-insensitive. Basically, the main improvement, compared to the old, simpler algorithm, is that letters are not required to be consecutive.

I'd still like to implement an even smarter completion matcher that also takes uppercase letters into account. However, I figured that this was a good start.