All these changes to avoid:
,----
| mu4e/meson.build:92: WARNING: Source item '/home/djcb/Sources/mu/build/mu4e/mu4e-meta.el' cannot be converted to File object, because it is a generated file. This will become a hard error in the future
`----
This is because we want to byte-compile a file we just before generated using
configure_file. This does not seem like a crazy thing, but meson threatens with
breaking the build at some point in the future.
So instead, we decide _not_ to compile this (very boring) file. But, users may
still have an older mu4e-meta.elc lying around, leading to confusion.
So, let's rename that file and we're golden.
Support the new batched query results from the mu server; these are much faster
to render (2-3x it seems).
Rearrange the code a bit to avoid byte-compiler warnings.
Obsolete mu4e-header-func, to be replaced by mu4e-headers-append-func.
Dirk-Jan C. Binnema