Refactoring to eliminate duplicate code.
Exception handling improvements.
Zero-fill unused space in fragmented values, making them easier to extend later.
Pre-calculate inode level capacities.
Fix race condition in fragment cache.
Add lock upgrade mode.
Rename to LockUpgradeRule.
Add lock upgrade rule tests.
Merge remote-tracking branch 'remotes/origin/master' into compact
Refactored I/O classes into separate package.
Added docs for io package.
Support a custom data storage layer.
Merge remote-tracking branch 'remotes/origin/master' into compact
Add config checks when using custom page array.
Fix recovery race conditions.
Moved and renamed encode/decode utility functions.
Merge remote-tracking branch 'remotes/origin/master' into compact

Conflicts:
	src/main/java/org/cojen/tupl/PageQueue.java