Open the composer full screen, as a setting (#401) (#404)

Settings > General > Composing has a new switch, "Open the composer full
screen". With it on, every new composer, whether a new message, reply,
forward or reopened draft, starts maximized. Restore still shrinks it to
a window. A draft put back after an undone or failed send keeps the size
it had. It's off by default, and on a phone, where the composer already
fills the screen, it changes nothing.

One new string, translated in all nine catalogs. The count falling back
to English stays at 16 in every language.

Fixes #401

web/src/locales/de.ts

@@ -754,6 +754,7 @@ export const catalog: Catalog = {
     "Attachment reminder": "Anhang-Erinnerung",
     "Warn when the message mentions an attachment but none is attached.": "Warnen, wenn die Nachricht einen Anhang erwähnt, aber keiner angehängt ist.",
     "Spell check while typing": "Rechtschreibprüfung während der Eingabe",
+    "Open the composer full screen": "Nachrichten im Vollbild verfassen",
     "Confirm before deleting": "Vor dem Löschen bestätigen",
     "Show message snippets": "Nachrichtenvorschau anzeigen",
     "Preview the first line of each message in the list.": "Die erste Zeile jeder Nachricht in der Liste anzeigen.",