clone_schema function

I noted there was an inquiry as to how to copy or clone_schema
an entire schema. The standard method for doing that is to
1. pg_dump the schema in plain format
2. edit the dump file and change all occurrences of the schema name
3. reload the dump into the new schema.

The attached function is an alternate method for doing that.
It is a revision of the clone_schema by by Emanuel '3manuek'
from https://wiki.postgresql.org/wiki/Clone_schema

Originally, it did not copy views, functions or data from
the source schema despite the claim that it "copies everything".

I've added error checking and verified that it now copies the
current sequnce values, table data, views and functions.

As always, use with caution.
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