Add core unicode functionality.

Add utf-8 processing routines.
Change ecma_char_t from char/uint16_t to uint16_t.
Apply all utf-8 processing routines.
Change char to jerry_api_char in API functions' declarations.

JerryScript-DCO-1.0-Signed-off-by: Andrey Shitov a.shitov@samsung.com

jerry-core/rcs/rcs-recordset.h

@@ -311,7 +311,10 @@ public:
    */
   void skip (size_t size) /**< number of bytes to skip */
   {
-    access (ACCESS_SKIP, NULL, size);
+    if (size)
+    {
+      access (ACCESS_SKIP, NULL, size);
+    }
   } /* skip */
 
   /**