(DECODE_POSITION): New macro.

(DECODE_POSITION): New macro.
(CHAR_TO_BYTE, BYTE_TO_CHAR): New macros.

(BEG_BYTE, BEGV_BYTE, PT_BYTE, GPT_BYTE)
(ZV_BYTE, Z_BYTE): New macros.
(BUF_BEG_BYTE, BUF_BEGV_BYTE, BUF_PT_BYTE, BUF_GPT_BYTE)
(BUF_ZV_BYTE, BUF_Z_BYTE): New macros.
(BUF_GAP_END_ADDR): New macro.
(BEGV_ADDR, PT_ADDR, GPT_ADDR, GAP_END_ADDR, ZV_ADDR, Z_ADDR):
Use the new ..._byte buffer data.
(BUFFER_CEILING_OF, BUFFER_FLOOR_OF): Likewise.
(BUF_GPT_ADDR, BUF_Z_ADDR): Likewise.
(SET_PT_BOTH, TEMP_SET_PT_BOTH): New macros.
(SET_PT, TEMP_SET_PT, BUF_SET_PT, BUF_TEMP_SET_PT):
Call functions with new arg order.
(SET_BUF_BEGV, SET_BUF_BEGV_BOTH): New macros.
(SET_BUF_PT): Macro deleted.
(SET_BUF_ZV): Set charpos and bytepos.
(SET_BUF_ZV_BOTH, SET_BUF_PT_BOTH): New macros.
(BYTE_POS_ADDR): Renamed from POS_ADDR.
(CHAR_POS_ADDR): New macro.
(FETCH_BYTE): Use BYTE_POS_ADDR.
(FETCH_MULTIBYTE_CHAR): Use ..._BYTE macros.
(BUF_CHAR_ADDRESS): Convert charpos to bytepos.
(BUF_BYTE_ADDRESS): New macro, like the old BUF_CHAR_ADDRESS.
(PTR_BYTE_POS): Renamed from PTR_CHAR_POS.
(BUF_PTR_BYTE_POS): New macro.
(BUF_FETCH_CHAR, BUF_FETCH_BYTE, BUF_FETCH_MULTIBYTE_CHAR): New macros.
(struct buffer_text): New fields gpt_byte, z_byte.
(struct buffer): New fields pt_byte, begv_byte, zv_byte.