Definition of Contracts/ContractPrincipal is circular, overrestrictive and unclear

[rivettp]

The definition is somewhat circular in that it uses "principal" to define "Principal"
Also "first" is unclear here (earliest in time? precedence?), and it seems unnecessary given the emphasis on principal. If it's a synonym then make it such.
Finally there may be more than one principal in a contract (e.g. see ContractThirdParty) so "the principal" and "the first party" is too strong.

Originally posted by @rivettp in https://github.com/edmcouncil/fibo/diffs/15

[trypuz]

Links to concepts discussed in this issue:

• contract principal
• contract third party

BTW, we have 3 concepts labeled "principal" in FIBO now.

[trypuz]

@rivettp could you propose the first draft of the new definition, please?