The main motivation behind this is to cleanup the WhitespaceManager and make it more extensible for future alignment etc. features. Specifically, WhitespaceManager has started to copy more and more code that is already present in FormatToken. Instead, I think it makes more sense to actually store a reference to each FormatToken for each change.
This has as a consequence led to a change in the calculation of indent levels. Now, we actually compute them for each Token ahead of time, which should be more efficient as it removes an unsigned value for the ParenState, which is used during the combinatorial exploration of the solution space.
No functional changes intended.
Perhaps add an assert that we don't underflow.