ibuffer: New filters and commands

ibuffer: New filters and commands

Add several new filters and improve documentation.
See discussion on:
https://lists.gnu.org/archive/html/emacs-devel/2016-11/msg00399.html
* lisp/ibuf-ext.el: Add paragraph to file commentary.
(ibuffer-saved-filters, ibuffer-filtering-qualifiers)
(ibuffer-filter-groups): Update doc string.
(ibuffer-unary-operand): Add new function that transparently
handles 'not' formats for compound filters.
(ibuffer-included-in-filter-p): Handle 'not' fully; update doc string.
(ibuffer-included-in-filter-p-1): Handle 'and' compound filters.
(ibuffer-decompose-filter): Handle 'and' as well,
and handle 'not' consistently with other uses.
(ibuffer-and-filter): New defun analogous to 'ibuffer-or-filter'.
(ibuffer--or-and-filter): New defun.
(ibuffer-or-filter, ibuffer-and-filter): Use it.
(ibuffer-format-qualifier): Handle 'and' filters as well.
(ibuffer-filter-by-basename, ibuffer-filter-by-file-extension)
(ibuffer-filter-by-directory, ibuffer-filter-by-starred-name)
(ibuffer-filter-by-modified, ibuffer-filter-by-visiting-file):
Add new pre-defined filters.
(ibuffer-filter-chosen-by-completion): Add new interactive command
for easily choosing a filter from the descriptions.
* lisp/ibuffer.el (ibuffer-mode-map):
Bind ibuffer-filter-by-basename, ibuffer-filter-by-file-extension,
ibuffer-filter-by-starred-name, ibuffer-filter-by-modified,
ibuffer-filter-by-visiting-file to '/b', '/.', '/*', '/i', '/v'
respectively; bind 'ibuffer-or-filter', 'ibuffer-and-filter',
'ibuffer-pop-filter' ,'ibuffer-pop-filter-group' and
'ibuffer-filter-disable' to '/|', '/&', '/<up>', '/S-<up>'
and '/ DEL' respectively.
* test/lisp/ibuffer-tests.el (ibuffer-autoload): Add appropriate
skip specification.
Add menu entries for the new filters.
(ibuffer-filter-inclusion-1, ibuffer-filter-inclusion-2
ibuffer-filter-inclusion-3, ibuffer-filter-inclusion-4
ibuffer-filter-inclusion-5, ibuffer-filter-inclusion-6
ibuffer-filter-inclusion-7, ibuffer-filter-inclusion-8
ibuffer-decompose-filter, ibuffer-and-filter
ibuffer-or-filter): Add new tests; they are skipped unless
ibuf-ext is loaded.
; * etc/NEWS: Add entries for new user-facing features.