Accept common architecture aliases for arch options instead of only
accepting the canonicalized, OS-independent architecture name. This
restores compatibility with existing projects and may simplify option
handling for projects that only target a single OS (and thus, do not
need OS-independent architecture names).

Accept common architecture aliases for the sandbox config for
consistency with arch options.

Accept architecture aliases

See merge request !1034

contributing: fix 'oprtation' and some other typos

See merge request !1055

The algorithm adds elements to a dictionary and then sorts the dictionary
by the discovered depths while recursing - using an OrderedDict is enough
to ensure a stable order.

This fixes `bst show --deps plan ...` reporting different results on
each invocation.

This fixes an aspect of #824

Added a function to report the list of elements which appeared in
a given queue in the order of their first appearance.

For each sample project and expected result order, this test ensures that:

  * bst show --deps plan: Always shows the expected build order.

  * bst build: Always builds in the expected order.