add man pages for sxinit and sxreport-client
add man pages for sxvol and sxrev
Improve sxls efficiency by storing previous query result in memory and skipping unnecessary queries.

This improvement let database to take advantage of indexing and reduces
redundant queries. More text processing is done inside sqlite engine
than it was done before.
Use only one query for non-recursive listing. Retry if got the same file name. For testing.
Rework listing
Fix bad reset while failing file upload