Rename aloc to eoc

[jtfmumm]

aloc shows up in the code in relation to sources, sinks, and connectors. This meant "at least once connectors", but it currently is also used for components that are better described as "effectively once" since they handle both at least once and at most once semantics. We should rename aloc to eoc unless there's a case where the component does not support at most once.

Marked as a bug only because this is misleading and could lead to mistakes down the line.