v0.4.0

• new irma server feature: static (e.g. printable) QRs that start preconfigured sessions, see documentation
• irma server now returns attribute issuance time to the requestor after the session has finished
• hopefully fix “unknown or expired session” errors that would sometimes occur in the IRMA app in bad network conditions
• combined issuance-disclosure requests with two schemes one of which has a keyshare server now work as expected
• other bugfixes