vchoi_fork

[svn-r8853] Purpose:
    Code optimization

Description:
    Refactor B-tree code to extract all common information for a B-tree into a
shared structure that is pointed to by all the nodes in tree (instead of being
included in each node).

    Also re-order B-tree node comparison checks for chunked datasets to
check for >= the upper node first, since the comparison is a bit "heavy" and
this check is more likely to succeed when you are adding records to the
dataset.

Platforms tested:
    Solaris 2.7 (arabica)
    FreeBSD 4.10 (sleipnir) w/parallel
    Too minor to require h5committest
    (also, recent h5dump commits have broken testing...)