* fix copying of the extents of the metadata node to the metadatamirror node;
it was not copying all extents.
* fix truncing metadata partition:
* fix endian conversions
* fix information length calculation so its truncated to the right length!
* allow for setting maximum extent length in extent merging. This is needed
since extents in the metadata partition files are only to be in allocation
unit sizes.
* adjust grow and shrink node to set the granularity of the maximum length of
an extent when encountering a metadatafile or metadatamirror file.