Added --namespace option to set the namespace of repacked tables

Bumped version number to enforce extension re-creation as the SQL has
been modified.

Current limitations:

- Check for namespace existence: on error temp objects are left around
- What happens to the indexes?
- Tests needed.
- Should the default be the GUC default_tablespace instead of pg_default?
  This is actually an original pg_repack shortcoming, not a regression.
Added --moveidx command line option

The option is only parsed, not implemented yet.
Added tests for the namespace change feature

Currently not passing as --moveidx not implemented yet.
Merge branch 'master' into change-tablespace
Added check for target tablespace existence
Added implementation for --moveidx

Note: if original namespace is "foo bar", repack_indexdef gives a bad
result. This is weird as apparently skip_ident can deal with spaces in
a quoted identifier. Committing as I'm going home, will deal with that
later.
Fixed index definition tokenization

In the previous commit skip_const was going ahead the space thus removing the
starting quote. Also fixed (and tested) trailing part after the tablespace
name, e.g. the WHERE clause.
Added documentation for --tablespace and --moveidx
Merge branch 'change-tablespace'

Conflicts:
	bin/pg_repack.c
	doc/pg_repack.rst