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/parser/js/lexer.h

@@ -170,10 +170,7 @@ typedef struct
  */
 #define TOKEN_EMPTY_INITIALIZER {0, TOK_EMPTY, 0}
 
-void lexer_init (const char *, size_t, bool);
-void lexer_init_source (const char *, size_t);
-
-void lexer_free (void);
+void lexer_init (const jerry_api_char_t *, size_t, bool);
 
 token lexer_next_token (void);
 void lexer_save_token (token);