bug#16214: Consistency in dired-, occur-, and grep-mode

[Juri Linkov <juri@jurta.org>]

> To have consistency on edition of buffer at dired-/occur-/grep-mode,
> (1) addition of two key-binds, "e" to both (dired-toggle-read-only)
> and (wgrep-change-to-wgrep-mode), and (2) implementation of a function
> (occur-abort-changes) will do it.

I highly sympathize with your attempts to make keybindings consistent,
but please note that some existing keybindings can't be changed for
historical reasons.  For example, `v' in Dired opens a file in view mode,
so often I type `v' in vc-dir, but it registers the file in version
control instead of opening in view mode.  I have no idea how to avoid
this inconsistency.

Also `e' in Dired is used to open a file for editing, so `e' can't be
used to edit the Dired buffer.  Maybe take some other key, e.g.
`M-e' (like in isearch) or `M-g e'.

Inconsistency in opening in other window between Dired ("o") and
occur/grep (<RET>) is a good inconsistency, because the primary
purpose of occur/grep is to open files in other window, so
more easy to type key <RET> is more suitable for occur/grep
to open a file in other window.

I see no harm in adding "o" (`compile-goto-error') to grep,
as grep already has `C-o' (`compilation-display-error')
to display grep hits in another window.