Set parameters for group conversion
H5P.set_link_phase_change(gcpl_id,max_compact,min_dense) sets the parameters for conversion between compact and dense groups.
max_compact is the maximum number of links to store as header messages in the group header before converting the group to the dense format. Groups that are in the compact format and exceed this number of links are automatically converted to the dense format.
min_dense is the minimum number of links to store in the dense format. Groups which are in dense format and in which the number of links falls below this number are automatically converted back to the compact format.