preorder/register or register/renew. Also, when considering name
prices, use the preorder's block number (i.e. the epoch the preorder
occurred in determines the price to pay, not the register). For
renewals, however, use the current block height to determine the fee.
consensus fields (since the untrusted db might not have the data we
need when verifying). Also, when calculating consensus quirks, check if
a name operation is the first NAME_IMPORT for a name in order to handle
the NAME_IMPORT fee quirk correctly.
* identify and preserve invariant properties that must hold across name
state-transitions (like no-collisions, or limiting fields that can
change).
* add history validation
* identify consensus-bearing fields, and how each state-creation or
state-transition may affect them (and add runtime checks to see that
they only affect the fields we say they will)
* add decorators that we can apply to name operations to enforce the
above.
