protected from HAVE_XML not set
modified KHttpRetrier and its use in HttpFile to be reconfigurable from kfg
Merge branch 'engineering' of https://github.com/ncbi/ncbi-vdb into engineering
cleaned up 'make clean'
updated use of KHttpRetrier; now on reliable connections only and configurable from kfg
Merge branch 'engineering' of https://github.com/ncbi/ncbi-vdb into engineering