* lisp/tempo.el (tempo-define-template): Update documentation string
to mention that existing tags can be reassigned new templates.
(tempo-add-tag): Allow reassigning tags to new templates.
Additionally, invalidate tag collections in all buffers if the global
tags list is being modified.
(tempo-invalidate-collection): Allow invalidating tag collections in
all buffers at the same time.
* test/lisp/tempo-tests.el (tempo-define-tag-globally-test): Add a
test to check that new templates plus tags can be defined from any
buffer and then immediately used in other buffers.
(tempo-overwrite-tag-test): Add a test to check that tags can be
reassigned templates.
* etc/NEWS: Announce changes in tempo.el.
(Bug#39555)
For discussion, see the following thread:
https://lists.gnu.org/archive/html/emacs-devel/2019-05/msg00395.html
* lisp/tempo.el: Use lexical-binding.
(tempo-define-template): Expand documentation to mention
`tempo-user-elements'.
(tempo-local-tags, tempo-collection, tempo-dirty-collection)
(tempo-marks, tempo-match-finder): Define with defvar-local.
(tempo-named-insertions, tempo-region-start, tempo-region-stop): Make
them automatically buffer-local.
* test/lisp/tempo-tests.el: Add tests for tempo.el.
