Feature: drop ICU-lx in favour of directly interfacing with harfbuzz

This means we have RTL support again with ICU 58+. It makes use of:
- ICU for bidi-itemization
- ICU for script-itemization
- OpenTTD for style-itemization
- harfbuzz for shaping

src/gfx_layout_icu.h

@@ -11,6 +11,7 @@
 #define GFX_LAYOUT_ICU_H
 
 #include "gfx_layout.h"
+
 #include <unicode/ustring.h>
 
 /**