PricedCallSpread should accept longCollateralShare in basis points

[Chris-Hibbert]

What is the Problem Being Solved?

makeInvitationPair() in the PricedCallSpread contract takes the longCollateralShare in basis points, and then multiplies that by 100 to construct a percentMath in basis points for better precision. The caller should be able to provide 4 digits of accuracy, rather than just the two currently allowed.

Description of the Design

Change the name (e.g. to makeInvitations()) and deprecate makeInvitationPair().

Security Considerations

None

Test Plan

Add a test to show that the basis points value is handled.