[Yanel-usage] Improvements re reading and writing of revisions by Yarep

[Michael Wechner]

Hi

We recently had some issues regarding reaching the maximum number of
inodes.

In order to minimize the usage of inodes we made the splitting of
revision name and the date index implementation configurable, e.g.

<meta src="../data-repo/yarep-meta" revisions-path-type="flat"
revisions-date-index-impl="lucene"/>

If the attribute 'revisions-path-type' is not set, then the revision
name is splitted.

If the attribute 'revisions-date-index-impl' is not set, then the
directory implementation is used, which scales very well from a
performance point of view, but also needs a lot of inodes.

Enjoy

Michael