main/client: add --class, an alias for --app-id

This is to help e.g. scripts that wants to launch terminal instances
in a terminal agnostic way.

Many terminals were originally for X11, where the '--class' choice was
obvious. When they were ported to Wayland, it made sense for them to
keep the '--class' command line option, but have it set the
application ID instead (since "class" is not a thing on Wayland).

Let's add the alias, but minimally documented. We don't want to
_encourage_ its use after all.

Closes #2368

CHANGELOG.md

@@ -72,6 +72,14 @@
 
 ## Unreleased
 ### Added
+
+* Command line option `--class`, an alias for `--app-id`. Intended to
+  be used by scripts and similar that wants to launch terminal
+  instances in a terminal agnostic way ([#2368][2368]).
+
+[2368]: https://codeberg.org/dnkl/foot/issues/2368
+
+
 ### Changed
 
 * Do not allow codepoints to be merged into grapheme clusters directly

client.c

@@ -157,6 +157,7 @@ main(int argc, char *const *argv)
         {"term",               required_argument, NULL, 't'},
         {"title",              required_argument, NULL, 'T'},
         {"app-id",             required_argument, NULL, 'a'},
+        {"class",              required_argument, NULL, 'a'},
         {"toplevel-tag",       required_argument, NULL, TOPLEVEL_TAG_OPTION},
         {"window-size-pixels", required_argument, NULL, 'w'},
         {"window-size-chars",  required_argument, NULL, 'W'},

doc/foot.1.scd

@@ -70,6 +70,9 @@ the foot command line
 	Value to set the *app-id* property on the Wayland window
 	to. Default: _foot_ (normal mode), or _footclient_ (server mode).
 
+*--class*=_ID_
+	Alias for *--app-id*.
+
 *toplevel-tag*=_TAG_
 	Value to set the *toplevel-tag* property on the Wayland window
 	to. The compositor can use this value for session management,

doc/footclient.1.scd

@@ -33,6 +33,9 @@ terminal has terminated.
 	Value to set the *app-id* property on the Wayland window
 	to. Default: _foot_ (normal mode), or _footclient_ (server mode).
 
+*--class*=_ID_
+	Alias for *--app-id*.
+
 *toplevel-tag*=_TAG_
 	Value to set the *toplevel-tag* property on the Wayland window
 	to. The compositor can use this value for session management,

main.c

@@ -216,6 +216,7 @@ main(int argc, char *const *argv)
         {"term",                   required_argument, NULL, 't'},
         {"title",                  required_argument, NULL, 'T'},
         {"app-id",                 required_argument, NULL, 'a'},
+        {"class",                  required_argument, NULL, 'a'},
         {"toplevel-tag",           required_argument, NULL, TOPLEVEL_TAG_OPTION},
         {"login-shell",            no_argument,       NULL, 'L'},
         {"working-directory",      required_argument, NULL, 'D'},