common: added nv_filename_ext; renamed get_system_arch -> nv_get_system_arch
go: used nv_get_system_arch instead of get_system_arch
fixed nv_get_filename_ext; fixed some tests
fixed mk (works with any file ext); added plug_unpack/plug_configure
update README
'mk': imporoved logic; added 'plug_download' for plugins
common: renamed get_cmd_name/nv_cmd_name bold/nv_bold
common: renamed show_desc/nv_show_desc show_usage/nv_show_usage
common: renamed lpad/nv_ladp rpad/nv_rpad
common: renamed get_plugin_name/nv_get_plugin_name get_plugin_version/nv_get_plugin_version
common: renamed filename/nv_get_filename
common: renamed get_cpu_count to nv_get_cpu_count
common: renamed get_time/get_time_diff to nv_get_time/nv_get_time_diff
removed common:get_activate_script_path
common: renamed get_env_info_path to nv_get_env_info_path
common: renamed get_env_full_path/get_plugin_full_path to nv_get_env_full_path/nv_get_plugin_full_path
erlang-plugin: fixed sorting for command 'ls-versions'
added 'nv_' prefix to all common functions
added 'do' commands
added '--on' option into 'mk' command