UTF8 Text Display and Editor: added tons of tests for utf8 alignment,…

… fixed a bunch of methods that did not understand utf8. Still lots of places to visit.

git-svn-id: file:///fltk/svn/fltk/branches/branch-1.3@7800 ea41ed52-d2ee-0310-a9c1-e6b18d33e121

FL/Fl_Text_Buffer.H

@@ -33,6 +33,17 @@
 #ifndef FL_TEXT_BUFFER_H
 #define FL_TEXT_BUFFER_H
 
+
+#define ASSERT_UTF8
+
+#ifdef ASSERT_UTF8
+# include <assert.h>
+# define IS_UTF8_ALIGNED(a) if (a && *a) assert(fl_utf8len(*(a))>0);
+#else
+# define IS_UTF8_ALIGNED(a)
+#endif
+
+
 /*
  Suggested UTF-8 terminology for this file:
  
@@ -736,6 +747,11 @@ public:
   char *next_char(char *c) const;
   const char *next_char(const char *c) const;
 
+  /**
+   Align an index into the buffer to the current or previous utf8 boundary.
+   */
+  int utf8_align(int) const;
+
 protected:
 
   /**