Add title_align config directive

Controls the window titles alignment in title bars. Possible values are:
- left
- center
- right

Co-authored-by: Orestis Floros <orestisf1993@gmail.com>
- Made title_align a config directive instead of a command. Helps with
some tree_render() issues we had.
- Made title_max_width the same for all 3 cases.
- Modified title offset calculations and added explanations for each
case.
- Append title_padding to mark_width if a mark exists.

Fixes #1750

src/config_directives.c

@@ -318,6 +318,18 @@ CFGFUN(focus_on_window_activation, const char *mode) {
     DLOG("Set new focus_on_window_activation mode = %i.\n", config.focus_on_window_activation);
 }
 
+CFGFUN(title_align, const char *alignment) {
+    if (strcmp(alignment, "left") == 0) {
+        config.title_align = ALIGN_LEFT;
+    } else if (strcmp(alignment, "center") == 0) {
+        config.title_align = ALIGN_CENTER;
+    } else if (strcmp(alignment, "right") == 0) {
+        config.title_align = ALIGN_RIGHT;
+    } else {
+        assert(false);
+    }
+}
+
 CFGFUN(show_marks, const char *value) {
     config.show_marks = eval_boolstr(value);
 }