Update bdwgc gc library download page.
lynx has now a default tar.gz extension.
nxlog 1.4 non-2.0 has to be fetched from a mirror.
sqlite is now downloaded in /2014/.
Introduces refreshpkgs to make_env.sh.
Modify _pkgs folder when refreshing.
Protect build_item for refreshpkgs set to 0 only.
Protect update_cache against update if refreshpkgs is in progress.
get_sources_from_web() get or link when refreshing.
getJDK gets or links when refreshing.