Standard module import

[connorjacobsen]

In conjunction with #3, there should be a way to include some of the built-in functions. It should provide a simple import, such as:

import Std

main : Int {
  printf("%d", 42)
}

[connorjacobsen]

Should consider implementing some sort of namespace functionality to go along with this.

It may be okay to dump everything into the same namespace initially, but it would certainly be better to have distinct namespaces for separate code modules.