Recompute volume sizes only on success
Restore --check option for sxadm

Avoid making automatic index by sqlite and create one in place
Report number of encountered errors after hashfs checking
upgrade to sqlite 3.8.7.1
change allocation of arrays
Introduce data extraction from node

Add --extract option to sxadm

Add sx_hashfs_extract() which takes all volumes, for which given node is
a volnode, iterate over all files stored in meta databases and try to
copy blocks to files stored in directories called with volume name.
add copying file through two volumes