Ben Gruver d1662b67fe Refactor dexbacked implementations
Made construction of a new dexbacked item as light weight as possible,
only the very mimimum in computed/stored. Some of the values that were
previously calculated/loaded in the constructor are now lazily loaded
upon first use.

In general, nothing is cached, unless the item can't be fully read by
the consumer without causing the value to be computed multiple times.
Otherwise, it is up to the consume to decide if/when/what they want to
cache.
2012-11-03 18:06:41 -07:00
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2012-11-03 18:06:41 -07:00