Add flags set to true when metadata/sections changed in the current frame
Add option to set the max file size at import time
Replace mkdir with mkpath
Add helper test function for tests testing the parent/child relationships
Add an explicit close tag to mark the end of a file/sequence of split files

Will be used by the incremental report aggregator to discard intermediate
state for a "done" subprocess.
Add a function to check whether Devel::StatProfiler is running
More concise test setup