* parse.y: encoding aware parsing.

* parse.y (pragma_encoding): encoding specification pragma.

* parse.y (rb_intern3): encoding specified symbols.

* string.c (rb_str_length): length based on characters.  
  for older behavior, bytesize method added.

* string.c (rb_str_index_m): index based on characters.  rindex as
  well.

* string.c (succ_char): encoding aware succeeding string.

* string.c (rb_str_reverse): reverse based on characters.

* string.c (rb_str_inspect): encoding aware string description.

* string.c (rb_str_upcase_bang): encoding aware case conversion.
  downcase, capitalize, swapcase as well.

* string.c (rb_str_tr_bang): tr based on characters.  delete,
  squeeze, tr_s, count as well.

* string.c (rb_str_split_m): split based on characters.

* string.c (rb_str_each_line): encoding aware each_line.

* string.c (rb_str_each_char): added.  iteration based on
  characters.

* string.c (rb_str_strip_bang): encoding aware whitespace
  stripping.  lstrip, rstrip as well.

* string.c (rb_str_justify): encoding aware justifying (ljust,
  rjust, center).

* string.c (str_encoding): get encoding attribute from a string. 

* re.c (rb_reg_initialize): encoding aware regular expression

* sprintf.c (rb_str_format): formatting (i.e. length count) based
  on characters.

* io.c (rb_io_getc): getc to return one-character string.
  for older behavior, getbyte method added.

* ext/stringio/stringio.c (strio_getc): ditto.

* io.c (rb_io_ungetc): allow pushing arbitrary string at the
  current reading point.

* ext/stringio/stringio.c (strio_ungetc): ditto.

* ext/strscan/strscan.c: encoding support.

git-svn-id: svn+ssh://ci.ruby-lang.org/ruby/trunk@13261 b2dd03c8-39d4-4d8f-98ff-823fe69b080e