ideas.txt

the interface that contracts must include must implement 

*some sort of custom action dispatcher. all action calls coming from the keyaccounts contract must be intercepted
*this custom dispatcher reads the transaction and figures out with which publickey the kaction is authenticated.
*if the dapp contract knows the publickey it can be handled as account identifier similar to an accountname

An other option would be to have a custom action in the dapp contract that functions as dispatcher and has the publickey in it's action args together with the kaction.
Because this custom action must require_auth from the keyaccounts contract the dapp contract can be sure the publickey can be trusted.
the dapp contract can then execute the payload action on it's own

sadly there will be collisions if a publikey is converted to uint64_t/name. so the dapp contract must have a subaccount system.