This rebuilds indexes during compression and decompression. Previously,
indexes were not updated during these operations. We also fix
a small bug with orderby and segmentby handling of empty strings/
lists.
Finally, we add some more tests.
Replace custom parsing of order by and segment by lists
with the postgres parser. The segment by list is now
parsed in the same way as the GROUP BY clause and the
order by list in the same way as the ORDER BY clause.
Also fix default for nulls first/last to follow the PG
convention: LAST for ASC, FIRST for DESC.
Add support for compress_chunks function.
This also adds support for compress_orderby and compress_segmentby
parameters in ALTER TABLE. These parameteres are used by the
compress_chunks function.
The parsing code will most likely be changed to use PG raw_parser
function.
