Merge pull request #395 from pgelinas/cachable-delegate

Made DelegatingDeserializer also delegate isCachable by default.
Merge pull request #394 from pgelinas/custom-object-id-serialization

Support for custom object id serialization by subclasses.
documentation for deserialization versus polymorhism.
Merge pull request #396 from benson-basis/master

documentation for deserialization versus polymorphism.
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Update README.md

Fixed extra space that broke up a word.
Merge pull request #397 from Mgamerz/patch-1

Update README.md
Fix #398 for mainline (2.4)
Bit more rearranging; trying to reduce use of inner classes for shared things (only leave inner classes for private use)
Implementation of custom object id resolution.