config-parser: Make get_bool be bool

Wayland innovated a lot of cool things, but non-binary boolean values is
the great advances of our time.

Make config_parser_get_bool() work on boolean values, and switch all its
users.

Signed-off-by: Daniel Stone <daniels@collabora.com>

desktop-shell/shell.c

@@ -464,7 +464,7 @@ shell_configuration(struct desktop_shell *shell)
 {
 	struct weston_config_section *section;
 	char *s, *client;
-	int allow_zap;
+	bool allow_zap;
 
 	section = weston_config_get_section(wet_get_config(shell->compositor),
 					    "shell", NULL, NULL);