Cleanup swim wrapper

[baltzell]

In preparation for new swimming versions,

• Move stoppers to a new, separate class
• Move parameter setup to a new, separate class
• Create ISwim interface of appropriate methods from Swim
• Create abstract ASwim for other shared stuff and generic wrapping for some simple geometry calls
• Old Swim and new AdaptiveSwim classes now extend ASwim
• Move existing adaptive methods to AdaptiveSwim and add missing ones
• In the process, removed some unused Swim methods
• General cleanup