[links] Workshops: several CIRMMT event links unavailable

[kyuchia]

Several CIRMMT event links referenced on SIMSSA workshop entries appear unavailable or no longer resolve to original content.

Cases noted (examples):

• Workshop on SIMSSA IV: ONRP and Cantus Ultimus (CIRMMT, Sep 29, 2014)
  Current (unavailable): https://www.cirmmt.org/en/events/workshops/research/simssa0914/event

• Workshop on SIMSSA II (CIRMMT, Jul 28, 2012)
  Current (unavailable): https://www.cirmmt.org/en/events/workshops/research/simssa/event

• CIRMMT Workshop: Processing Large Amounts of Musical Information (Feb 17, 2012)
  Current (unavailable): https://www.cirmmt.org/en/events/workshops/research/musical-info/event

• Cantus Ultimus Workshop (CIRMMT, Sep 8, 2012)
  Current (unavailable): https://www.cirmmt.org/en/events/workshops/research/ra3120908/event

Questions

• Should we annotate these as (link unavailable), or remove the links?