Somewhere along the way, the body-txt and body-html fields were merged
into a single body field. Later, commit 8eac392221 ("guile: re-enable
the guile support") finally removed support for Field::Id::BodyHtml from
mu:c:get-field.
Unfortunately mu.scm and the documentation are still stuck in the past, so
update them. mu:body-txt is now a synonym for mu:body, and mu:body-html
always returns #f.
I wanted to add a mu:body test also for the rfc822.1 message, but there's
currently a bug where its body text is is duplicated (issue #2802), so the
test would fail.
Since 2008, autotools has served us well - thank you!
However, mu is now using meson build, and it's time to remove the
autotools support -- one build system is enough.
The previous implementation of `msg-graphs` called `mu:plots/mu:plot` with
output set to `#t` when the option `--text` was passed. This caused an error in
the `string-append` call in `mu:plot` since the expression `(or output "dumb")`
evaluated to the symbol `#t` rather than a string.
This commit fixes this by making sure that `mu:plot` is called with `output` set
to `"dumb"` when the option `--text` is passed to `msg-graphs`, and with
`output` set to `"wxt"` (the default multi-platform graphical output device in
`gnuplot`) otherwise. This is done by essentially making the code of
`msg-graphs` agree with the plotting code in the `guile/scripts` directory.
