Many of the external links found in the notmuch source can be resolved
using https instead of http. This changeset addresses as many as i
could find, without touching the e-mail corpus or expected outputs
found in tests.
The notmuch cli program and emacs lisp versions may differ (especially
in remote usage). It helps to resolve problems if we can determine
the versions of notmuch cli and notmuch emacs mua separately.
The build process now creates notmuch-version.el from template file
by filling the version info to notmuch-emacs-version variable.
