Compare sortText length before compareToIgnoreCase in LSCompletionProposalComparator

[zulus]

compareToIgnoreCase produces wrong order. For example server response 15 and 5 sortText. After compareToIgnoreCase 5 will be before 15, when should be after

[zulus]

I checked deeper into code and see two issues:

1. DocumentFilter have main priority, and this is a reason why I sometimes have strange results in JS files after "dot" or operators
2. Completions aren't re-sorted after filtering. CompletionProposalPopup#computeFilteredProposals just show/hide proposals, so in current state, if completion was invoked after first letter (for example new d|), and filtered is based on letters only (position isn't re-checked) most of completions have no sense, and it's mostly noise!