The TagbarKind syntax match pattern has a zero-width look-behind atom
with unlimited length. This can slow down syntax highlighting. Since in
this case there can only be 1 or 2 characters that get matched, we can
set a limit for the match, thus speeding up the matching.
Since the limit unfortunately works with bytes instead of characters,
use 3 instead of 2 to account for double-width folding characters.
When g:tagbar_iconchars = ['+', '-'] (default on Windows), and viewing a filetype (e.g. java) that has visibility information (i.e. the [-+#] sigils), the method is mistakenly highlighted as TagbarKind. Restrict its matches to when the sigil is at the beginning of the line to avoid the false matches at the indented method tags.
When there's a tag e.g. "foo-bar", the "-bar" part is matched as TagbarKind. Add a zero-width condition to all sigil patterns that allow only whitespace characters before the sigil.
