complete lua rework, also module path fix

This is a complete rework of the lua package, it also allows the
environment modification classes to handle paths that are not separated
by colons, and uses the support for same in TCL modules as well.

The biggest difference is the handling for lua extension packages, which
now have their paths set correctly by the lua parent package, and have
access to both lua and luarocks as installation tools. See the luaposix
package for what should be required for most lua packages after this.

var/spack/repos/builtin/packages/lua-luaposix/package.py

@@ -0,0 +1,16 @@
+from spack import *
+import glob
+
+class LuaLuaposix(Package):
+    """Lua posix bindings, including ncurses"""
+    homepage = "https://github.com/luaposix/luaposix/"
+    url      = "https://github.com/luaposix/luaposix/archive/release-v33.4.0.tar.gz"
+
+    version('33.4.0', 'b36ff049095f28752caeb0b46144516c')
+
+    extends("lua")
+
+    def install(self, spec, prefix):
+        rockspec = glob.glob('luaposix-*.rockspec')
+        print rockspec
+        luarocks('--tree=' + prefix, 'install', rockspec[0])