Cutover all 'UInt32' to 'Int32' as well as integer literals. Remove casts using 'uint32', although some of the backward casts using 'int32' may have been overlooked - will check before next commit.
Update test failure reproduction string to track changes in the test case generation algorithm.
Removed remaining redundant usages of 'int32' casts. Overall, performance has improved across the board for the unit tests in comparison with the parent commit that this branch was based on. Result!
Merge in removal of UInt32 in APIs and implementation.