moved coverageVariableName to a static field in Config
ConcurrentHashMultiset -> regular HashSet, don't need the other one here
moved InstrumentingNodeVisitor to an outer package-local class. Moved ScriptInstrumenter and InstrumentingNodeVisitor to the instrumentation package
Refactored package structure (if I can call it that). Some more refactoring here and there.
Moved defaults out of the config concrete class into the interface
issue #81: updated default browser version to FIREFOX_17 (FIREFOX_3_6 and FIREFOX_10 are deprecated as of htmlunit 2.12