Implement import a, b, c from foo syntax

This brings stuff into the local scope, but it is a little funky with
local scopes that are above the current level (in the same function or
module).

Signed-off-by: Alek Ratzloff <alekratz@gmail.com>

tests/modules.npp.expect

@@ -3,3 +3,6 @@ importing test_import_local
 1
 2
 3
+1
+2
+3