fixed 'nv off' to work with new shell
common: added nv_semver_get_(major|minor|patch|special)
added common: nv_echo_err
Merge branch 'master' of github.com:ekalinin/envirius
added plugin for php
added plugin for haskell-prebuilt
update README
update CHANGELOG
improved common: nv_get_plugin_version; handle empty version
improved command 'mk': handle not exists plugins
update CONTRIBUTORS
0.7.2