IDEA-58130 Improve editor performance during working with large files written in a single line

Make logicalPositionToOffset calculations faster for long lines (when soft wraps are enabled).
Position calculations are more consistent now so this is also supposed to fix EA-53787.
IDEA-58130 Improve editor performance during working with large files written in a single line

Remove unneeded code: offset to logical line mapping doesn't depend on soft wraps.
IDEA-131953 Multiple carets misbehave when auto completion dropdown opens
IDEA-100878 Emacs Tab behaves strange when indenting with tabs
no need to blur tab text
IDEA-125016 Commenting out a line in an XML file with commented out comments lower in the file can cause unwanted changes (and invalid xml). REGRESSION
Testing framework now allows checking only specified warnings and highlightings
ignore inferred @NotNull when there's external @Nullable