Some cleanups and attempts at improving code-readability and -extensibility:

Some cleanups and attempts at improving code-readability and -extensibility:
* added inner holder class to BreakingAlgorithm to contain everything related to the fitness classes. Improves readability of both the code and the trace messages.
* extracted blocks of code in BreakingAlgorithm.findBreakingPoints() into protected methods. Following the already existing handleBox(), added handleGlueAt() and handlePenaltyAt() to provide extension points to subclasses. Extraction of the code-blocks related to the node-recovery mechanism.
* extracted blocks of code in BreakingAlgorithm.considerLegalBreak() into protected methods: deactivateNode(), activateNode() and forceNode()
* factored the functionality to obtain the index of the first box into KnuthSequence... just seemed to make sense; may be useful elsewhere.
* some (but not all :() javadoc fixups
* minor changes to LineLayoutManager and PageBreakingAlgorithm to take into account above changes

git-svn-id: https://svn.apache.org/repos/asf/xmlgraphics/fop/trunk@790142 13f79535-47bb-0310-9956-ffa450edef68