Prefer the form `run/load script… as alias`.

Prefer `run script… as alias` and `load script… as alias`
to `run script file…` and `load script file…`.
In some cases the latter form may give less clear
error messages than the former (i.e., “can't make
object of type reference” vs “File was not found”).
Prefer `run/load script… as alias` (more instances).
Fix `asmake build` task.