a buffer of classes for primitive types added to PKVM, but they'll
not be initialized in this commit.
names buffer and constant pool of a module are now merged (just like
java's constant pool).
VM's core libraries and scirpt modules are merged into a single
map name modules.
creating a new module doesn't register it automatically anymore,
you need to call pkRegisterModule(...) each time.
newModule() function refactored with a simpler interface, we're not
setting path or registering globals anymore, the caller is
responsible for that.
now it's easier to re-use cli modules into another hosting
application and a little python script have added to generate
native api to support native extension library.
