rebase with upstream release 0.35
    
    bz #2030690
    
    Library
    -------
    
    Implement the `date` and `lastmod` fields in the S-expression parser.
    
    Ignore trailing `/` for pathnames in both query parsers.
    
    Rename configuration option `built_with.sexpr_query` to
    `built_with.sexp_queries`.
    
    Do not assume a default mail root in split (e.g. XDG) configurations.
    
    Fix some small memory leaks in `notmuch_database_open_with_config`.
    
    CLI
    ---
    
    Improve handling of leading/trailing punctation and space for
    configuration lists.
    
    Only ignore `.notmuch` at the top level in `notmuch new`.
    
    Optionally show extra headers in `notmuch show`. See
    `show.extra_headers` in notmuch-config(1).
    
    Emacs
    -----
    
    Drop `C-TAB` binding in hello mode, document `backtab`.
    
    Fix visual glitch in search mode by running `notmuch-search-hook`
    lazily.
    
    Don't add space to completion candidates, improves compatibility with
    third party completion frameworks.
    
    Make citation formating more robust against whitespace.
    
    Use `--excludes=false` when generating the 'All tags' section.
    
    Use cached copy of message body for `Fcc`, avoiding variant bodies for
    signed and/or encrypted messages.
    
    Add notmuch-logo.svg and use it in notmuch-hello view, replacing
    the .png version.
    
    Make header line in show buffers optional.
    
    Add customizable names for search buffers.
    
    Build
    -----
    
    Fix out-of-tree build for `python-cffi` bindings.
    
    Rearrange position of {C,CXX,CPP,LD}FLAGS, prevent some clashes with
    installed version of notmuch.
    
    Ignore more configure options.
    
    Test Suite
    ----------
    
    Replace some uses of `gdb` in the test suite with `LD_PRELOAD` based
    shims.
    
    Use `--with-colons` for gpgsm, fix compatibility with newer gnupg.
    
    Python bindings
    ---------------
    
    Add `matched` property to message objects.
    
    Users are reminded that the old python bindings in bindings/python are
    deprecated; this will probably be the last major release that ships
    them.
    
    Completion
    ----------
    
    Use `database.mail_root` for path completion in bash/zsh.