rewrite demandload module to be more flexible.
performance not affected.
old demandload module could only import top-level modules like os and
sys.
with rewrite, all of following syntax is emulated perfectly:
import foo, bar foo bar
import foo.bar.quux foo.bar.quux
from foo.bar import quux, blurfl foo.bar:quux,blurfl
only thing missing is "import foo as bar".
also, namespace clashes between placeholder object and demand loaded
module are no longer possible.
port:4:export
port:4:vaportight
port:4:import/export
FIXME: history is wrong here
port:1:1:-:eggs:import
port:1:2:+:eggs:vaportight
port:1:3:+:eggs:import/export
port:0:2:+:spam:export
port:0:1:+:spam:import
port:4:import/export