This patch adds support for "cell aliases": a cell alias allows a
single cell to be known by multiple names (one of them the primary).
This is useful in conjunction with AFSDB support, where you want all
the possible names for the same cell to share the same tokens, etc.
For instance, if the local resolver has "mit.edu" in its search
domain, an AFSDB lookup on cell "athena" will cause the primary
cell "athena.mit.edu" to be created, and "athena" made an alias
for it.
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