New stable version. Some small fixes and doc updates; big new thing are
the new SCM bindings (under scm/), which will replace the
long-deprecated old bindings (under guile/).

Overall:

- In 'mu init', --my-address has been renamed into --personal-address
  for consistency. The old name still works.

Mu4e:

- Emacs bookmarks can be now also be created for mu4e queries; see
  the mu4e-emacs-bookmark-policy defcustom

- Support dash when completing maildirs

- Add defcustom for mu4e-compose-jump-to-reasonable-place, so it can be
  overridden, e.g. in compose hooks.

- In mu4e, make indexing snappier when there no new messages

SCM:

- Experimental new Guile bindings under scm/, including a reference
  manual and unit tests.

The mac build broke (CI) because there's no conversion from time_t -> SCM
defined. Since we want to use int64_t anyway (2038), simply change to that.

Implement message->alist; i.e. to convert the mu4e-style plist into an idiomatic
alist. Add it as a message slot, initializing it lazily.

Update the message accessors to use the alist.

Add tests, docs.

Both in SCM and C++, use cc- for functions and objects defined in C++.
Makes it a little easier to track.

Use some snippet from
  https://git.wolfsden.cz/guile-wolfsden/tree/wolfsden/documentation.scm
and document some symbols (variables, classes etc.)

Get information about the store as an alist.

Scm + cc + test + doc.

Makes it easier to use elsewhere.

t by default (current behavior), but you can turn if off if your change (e.g.
compose-hook) wants to put the point in some different place.