more works on IPA

diacritics Overlay and Joiner has implemented

src/net/torvald/terrarumsansbitmap/GlyphProps.kt

@@ -21,6 +21,9 @@ data class GlyphProps(
         const val STACK_DOWN = 1
         const val STACK_BEFORE_N_AFTER = 2
         const val STACK_UP_N_DOWN = 3
+
+        const val DIA_OVERLAY = 1
+        const val DIA_JOINER = 2
     }
 
     constructor(width: Int, tags: Int) : this(