New transition effect syntax

Instead of this:
(cue 3
   (lighting-state ...)
   (crossfade 3 5))

We now have this:
(cue 3
   (crossfade 3 5
      (lighting-state ...)))

This makes a simple snap blackout very succinct:
(cue 6 (snap blackout))

1 files changed, 35 insertions, 0 deletions

diff --git a/guile/starlet/cue-part.scm b/guile/starlet/cue-part.scm
new file mode 100644
index 0000000..e98e422
--- /dev/null
+++ b/guile/starlet/cue-part.scm
@@ -0,0 +1,35 @@
+;;
+;; starlet/cue-part
+;;
+;; Copyright © 2020-2023 Thomas White <taw@bitwiz.org.uk>
+;;
+;; This file is part of Starlet.
+;;
+;; Starlet is free software: you can redistribute it and/or modify
+;; it under the terms of the GNU General Public License as published by
+;; the Free Software Foundation, either version 3 of the License, or
+;; (at your option) any later version.
+;;
+;; This program is distributed in the hope that it will be useful,
+;; but WITHOUT ANY WARRANTY; without even the implied warranty of
+;; MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+;; GNU General Public License for more details.
+;;
+;; You should have received a copy of the GNU General Public License
+;; along with this program.  If not, see <http://www.gnu.org/licenses/>.
+;;
+(define-module (starlet cue-part)
+  #:use-module (srfi srfi-9)
+  #:export (cue-part
+            <cue-part>
+            get-cue-part-state
+            get-cue-part-transition
+            set-cue-part-state!))
+
+
+(define-record-type <cue-part>
+  (cue-part state transition)
+  cue-part?
+  (state        get-cue-part-state
+                set-cue-part-state!)
+  (transition   get-cue-part-transition))