tuple count and v3 functions in psql for COPY

I tried to prepare a patch for these TODO items:
- Have COPY return the number of rows loaded/unloaded?
- Update [pg_dump and] psql to use the new COPY libpq API.

Added an "uint64 processed" to "struct CopyStateData". It's
incremented each time on a tuple send/receive made by
CopyTo/CopyFrom. Collected result is added to COPY command's
commandTag which can be gathered by PQcmdStatus(). (Also updated
PQcmdTuples() to work with it.)

When I tried to modify psql to print the COPY's commandTag, I found
that its implementation is really disorganized when we still use old
COPY commands. Thus replaced old COPY routines with the new ones.
(IMHO, modified design for the psql's COPY should work faster than
the previous. Because, in this patch, I don't read input one by one
with getc(). Just filled the buffer with fgets and made \r search
only in the first and last lines.)

Regards.

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