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This gives the revocation endpoints URL like "revocation/{action}/{parameters}", which is consistent with the session endpoints that were recently changed to "session/{sessiontoken}/{action}".

The URL to the server to which issuance records and revocation commands are sent now no longer needs to be put in the scheme, and may thus be kept private to the issuer. Instead multiple URLs are now in the scheme, which are only required to host revocation records for irmaclients and requestors to update their revocation state.

feat: switch to SQL revocation database for revocation server, and to simple in-memory database for requestors

Requestors only need to be aware of the last x revocation records and none of the other record types.

Addionally:
- pass revocation configuration into RevocationStorage
- refactor irma.NewConfiguration functions to use options struct
- split RevocationStorage helper functions into separate structs
- add credentialtype to revocation record wrapper in irmago

feat: support revocation sessions in IRMA server, and move revocation code from irmaconfig.go to its own file