Smaller lzo indexes: make #43 apply to current codebase

Make smaller lzo indexes by encoding the offsets instead of just writing them down naively.

Note this does not address any of @rangadi's comments from 2 years ago on #43, this is just bringing the PR up to a point where it can be applied to the mavenized build.
Not necessary at all, I think that was me trying to get the build to
pass....
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