Simplify layout of message viewer grid

This sub-grid was an artifact of an older design
Fetch plaintext part when replying
Use forked version of tcell
3445b80d — Kevin Kuehler 1 year, 5 days ago
widgets/terminal: Don't segfault on resize

vterm.Write and vterm.SetSize race when the window resizes, which
causing the underlying library to segfault.

Signed-off-by: Kevin Kuehler <keur@ocf.berkeley.edu>
Remove more GNU-isms from Makefile

Signed-off-by: Sam Whited <sam@samwhited.com>
Remove "wildcard" GNU-ism from Makefile

Signed-off-by: Sam Whited <sam@samwhited.com>
Add :save and :pipe commands to viewer

* :save takes a path and saves the current message part to that location
* :pipe is the same as pipe on the account page, but uses the current
  message part rather than the whole email (ie :pipe gzip -d)
* Refactored account:pipe and extracted common pipe code to
* Added helper command aerc.PushError
Update terminal color handling per vterm changes
Update to the latest go-libvterm
Update go-libvterm
Skip non selectable mailboxes in directory listing

If a MailboxInfo has the attribute \Noselect,
it is not possible to use this name as a selectable mailbox.

Therefore it should not be passed to the directory handlers.
The issue pops up if one has a hierarchy like this:

Even though lists is not a valid inbox (doesn't contain mail, only other maildirs)
it will show up in the directory listing, when we iterate over the MailboxInfo.

It does have the corresponding attribute set though and we can simply filter it out.
Add aerc-announce to README.md
Implement :edit in compose screen
msgviewer: copy stderr into pager

This prevents a broken filter config from being a silent error
Subsitute prefix in aerc.conf for install
Document :forward in aerc(1)
binds.conf: make reply -a easier to use than reply