Correct cardinality for element collector

[jklump]

Cardinality in schema is incorrect.

Role: Person who gets credit for picking location, getting funding, selecting and extracting the actual object. (1..N, nilable). ODP chief scientist, field geologist. Synthetic sample--experimentalist is collector.

[kitchenprinzessin3880]

Cardinality of collector has been set to 1:M nillable (collectors > collector); see dev branch