editor: make editor configurable via /executable

`/executable set editor /full/path/to/edit`.

Regards https://github.com/profanity-im/profanity/issues/1521

src/command/cmd_ac.c

@@ -1044,6 +1044,7 @@ cmd_ac_init(void)
     autocomplete_add(executable_ac, "avatar");
     autocomplete_add(executable_ac, "urlopen");
     autocomplete_add(executable_ac, "urlsave");
+    autocomplete_add(executable_ac, "editor");
 }
 
 void

src/command/cmd_defs.c

@@ -2508,7 +2508,8 @@ static struct cmd_t command_defs[] = {
       CMD_SUBFUNCS(
               { "avatar",  cmd_executable_avatar },
               { "urlopen", cmd_executable_urlopen },
-              { "urlsave", cmd_executable_urlsave })
+              { "urlsave", cmd_executable_urlsave },
+              { "editor", cmd_executable_editor })
       CMD_NOMAINFUNC
       CMD_TAGS(
               CMD_TAG_DISCOVERY)
@@ -2525,7 +2526,8 @@ static struct cmd_t command_defs[] = {
               { "urlopen set", "Set executable that is run by /url open. Takes a command template that replaces %u and %p with the URL and path respectively." },
               { "urlopen default", "Restore to default settings." },
               { "urlsave set", "Set executable that is run by /url save. Takes a command template that replaces %u and %p with the URL and path respectively." },
-              { "urlsave default", "Use the built-in download method for saving." })
+              { "urlsave default", "Use the built-in download method for saving." },
+              { "editor set", "Set editor to be used with /editor. Needs full file path." })
       CMD_EXAMPLES(
               "/executable avatar xdg-open",
               "/executable urlopen set \"xdg-open %u\"",
@@ -2533,7 +2535,8 @@ static struct cmd_t command_defs[] = {
               "/executable urlopen default",
               "/executable urlsave set \"wget %u -O %p\"",
               "/executable urlsave set \"curl %u -o %p\"",
-              "/executable urlsave default")
+              "/executable urlsave default",
+              "/executable editor set /usr/bin/vim")
     },
 
     { "/url",

src/command/cmd_funcs.c

@@ -9276,6 +9276,21 @@ cmd_executable_urlsave(ProfWin* window, const char* const command, gchar** args)
     return TRUE;
 }
 
+gboolean
+cmd_executable_editor(ProfWin* window, const char* const command, gchar** args)
+{
+    guint num_args = g_strv_length(args);
+
+    if (g_strcmp0(args[1], "set") == 0 && num_args >= 3) {
+        prefs_set_string(PREF_COMPOSE_EDITOR, args[2]);
+        cons_show("`editor` command set to invoke '%s'", args[2]);
+    } else {
+        cons_bad_cmd_usage(command);
+    }
+
+    return TRUE;
+}
+
 gboolean
 cmd_mam(ProfWin* window, const char* const command, gchar** args)
 {

src/command/cmd_funcs.h

@@ -241,6 +241,7 @@ gboolean cmd_url_save(ProfWin* window, const char* const command, gchar** args);
 gboolean cmd_executable_avatar(ProfWin* window, const char* const command, gchar** args);
 gboolean cmd_executable_urlopen(ProfWin* window, const char* const command, gchar** args);
 gboolean cmd_executable_urlsave(ProfWin* window, const char* const command, gchar** args);
+gboolean cmd_executable_editor(ProfWin* window, const char* const command, gchar** args);
 gboolean cmd_mam(ProfWin* window, const char* const command, gchar** args);
 gboolean cmd_editor(ProfWin* window, const char* const command, gchar** args);