v0.0.20 - Import.Alias + Apple Silicon build

v0.0.20

Added

• Added an Import.Alias built-in variable, usable inside packs, containing the
  alias under which the pack was imported. Consider the following import:

  Import:
     bar: github.com/bilus/foo

  When you run the task below, defined inside the foo pack, it'll print "bar":

  whoami: |
     echo ${Oya[Import.Alias]}

• Added build for Apple Silicon processors arm64.

Changed

• Report an error if a Require or Replace directive appears in an Oyafile
  without a Project directive; you can manage an Oya project dependencies in
  the top-level Oyafile.

Fixed

• Ensure non-zero exit code from a command in Oya tasks, including sub-commands,
  propagates to the shell invoking oya run, even without set -e.