5ba22c2ec9
1. rewrite of the Haven variation of the Pricing Record class to support: - versioning of the PR format - nested supply_data and asset_data structs - verification of the signature using a variable-length string (not R+S) 2. calculation of the slippage tallies for a block in add_block(), so that we can work out the yield that is due to be paid out for the block. Loads of little fixes and cleanups.