This commit is a fix of pgxc_ctl to assign coorect node as "PRIMARY".
Add support in pg_dumpall to dump existing nodes and groups.

The documentation is updated accordingly.
To dump existing nodes and node groups use --dump-nodes command line switch.
Add support in pg_dump & pg_dumpall to add TO NODE clause in CREATE TABLE statements.

The documentation is updated accordingly.
The command line switch to use is --include-nodes
Add support to block DDLs to take backup for new node addition in an existing Postgres-XC cluster.

The documentation is updated accordingly.
The patch adds a new system function called pgxc_lock_for_backup().
When locked the system does not allow DDLs with the exception of CREATE NODE.
Add support to restore existing database schemas on the new node to be added.

This is the last patch of the series to suport new node addition
to an existing Postgres-XC cluster. It provides a new command line option
--restoremode to postgres that is to be used while restoring existing schema
on the new node to be added.
Add steps to add a new node in documentation.
This commit is to fix potential GTM vulnerability when GTM crashes
and restarts afterwords.   This commit checks out such a restoration
point so that GTM can safely restarts after the crash.

No need to change any configuration and documentation.

	modified:   src/gtm/main/Makefile
	new file:   src/gtm/main/gtm_backup.c
	modified:   src/gtm/main/gtm_seq.c
	modified:   src/gtm/main/gtm_txn.c
	modified:   src/gtm/main/main.c
	new file:   src/include/gtm/gtm_backup.h
	modified:   src/include/gtm/gtm_seq.h
	modified:   src/include/gtm/gtm_txn.h