Force JRE 1.6-compatible code generation.
Internal optimization.
Added 'FLinkedHashSet'.

FLinkedHashMap.readObject was badly broken; fixed.

Removed FHashSet.first and .last -- what was I thinking?

Added a few tests for FLinkedHash{Set,Map}.

Voluminous but minor style cleanups (mostly changing "p" to "f" where
it abbreviated "Pure").