pgsql: Fix pgstattuple functions to use regclass-type as the argument.

Fix pgstattuple functions to use regclass-type as the argument.

This allows us to specify the target relation with several expressions,
'relname', 'schemaname.relname' and OID in all pgstattuple functions.
pgstatindex() and pg_relpages() could not accept OID as the argument
so far.

Per discussion on -hackers, we decided to keep two types of interfaces,
with regclass-type and TEXT-type argument, for each pgstattuple
function because of the backward-compatibility issue. The functions
which have TEXT-type argument will be deprecated in the future release.

Patch by Satoshi Nagayasu, reviewed by Rushabh Lathia and Fujii Masao.

Branch
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master

Details
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http://git.postgresql.org/pg/commitdiff/1dc118660b8f12d3bdec94b6f6e1068966ca62e9

Modified Files
--------------
contrib/pgstattuple/Makefile | 2 +-
contrib/pgstattuple/expected/pgstattuple.out | 84 +++++++++++++++++++++++++
contrib/pgstattuple/pgstatindex.c | 72 +++++++++++++++++++--
contrib/pgstattuple/pgstattuple--1.1--1.2.sql | 39 ++++++++++++
contrib/pgstattuple/pgstattuple--1.1.sql | 58 -----------------
contrib/pgstattuple/pgstattuple--1.2.sql | 79 +++++++++++++++++++++++
contrib/pgstattuple/pgstattuple.control | 2 +-
contrib/pgstattuple/sql/pgstattuple.sql | 14 +++++
doc/src/sgml/pgstattuple.sgml | 47 +++++++++++---
9 files changed, 324 insertions(+), 73 deletions(-)