Speed up memory use reports

Does the matching of frees to allocations and gather of active memory against labels in SWIFT, which speeds things up by a couple of orders of magnitude. The output files are still quite large, but need no further processing, so that is not a big issue. Other better features are that the memory time series is continuous, i.e. maintains value between dumps, so they can be viewed without rebasing. The end summaries are also for all active memory, not just the memory allocated in this step.

Minor changes:

• struct entry in cache.h changed to struct sort_entry, entry is a bit generic and clashes with the <search.h> struct of the same name (equally badly named).

• the post-processing scripts are removed as no longer needed and the documentation is updated.

The memory use of the code is large (10% of an EAGLE_50) run and there are a lot of small internal allocations. The latter could be improved with effort, if pooled indices instead of pointers where used.

Fixes #579 (closed)