made the shell look at libraries in _G.libs as well as just _G

exec/shell.lua

@@ -21,6 +21,8 @@ setmetatable(shenv,{__index=function(_,k)
  local fp = findPath(k)
  if _G[k] then
   return _G[k]
+ elseif _G.libs[k] then
+  return _G.libs[k]
  elseif fp then
   return function(...)
    local tA = {...}