vchoi_fork

[svn-r12774] Modified flush code in the metadata cache to allow it to
handle flush callbacks which can dirty other entries, and
resize and/or rename the target entry.

This feature is needed by the fractal heap code.

Also added associated test code.


H5Commit tested.  Test failed on heping, but the 
error appears to be a syntax error in an un-related
file.

Tests on copper & sol passed, along with tests on 
phoenix.