Sorting the list of user bookmarks requires care to ensure that Vim's
builtin sort function is called correctly. Previously, this function was
called incorrectly. This is why the sorting of bookmarks never worked.
The offending functions have been removed here and replaced with
"s:Bookmark.CompareBookmarksByName". To understand the necessity for
this change, read ":h sort()" for the requirements of the function
reference argument (esp., note that it must return -1, 0, or 1).
In addition to fixing this problem, the new comparison function will
inspect the "g:NERDTreeBookmarksSort" setting to determine whether
case-sensitivity is preferred in the sort. The documentation has been
modified to accurately reflect this adjustment. The change is also made
in such a way as not to break any existing configurations.
Fixes#361 ("My bookmarks aren't sorted").
0b65089122