hdf5-examples

Created a new directory Performance for Performance related examples.

h5slabwrite.c:
   Create two different files that use different write patterns of the chunks.
   One in row pattern, the other in random pattern.
h5slabread.c:
   Read one of the files created by h5slabwrite.  Different file will result
   in different read speed.
h5slab.h:
   Common definitions used by both h5slaberead.c and h5slabwrite.c.

Tested: jam, amani, linew, abe.