Clarity Fixes in v1.5

A few changes, based on thoughts over coffee:

• Clarified the role of the GM at the start of the session, before they start playing as the Boss.
• Clarified the effect of previous pitches on Recursion.

This is the kind of game where part of the fun is in deciding what's stated and what's merely implied (both for me as an author and for GMs running sessions) so I'm likely to fiddle with that balance more in the future, once more people have messed around with the system.