Gracefully handle pathological communication nets

When a communication net with only a single entry appears,
we previously stopped processing, leading to a complete
stop for _all_ intervals. Handle this case more gracefully
by propagating the error upwards. This requires patches to
snatm that have been upstreamed.

Signed-off-by: Wolfgang Mauerer <wolfgang.mauerer@siemens.com>
Create communication network directories from the main dispatcher

Don't erroneously rely on package snatm to create the directories.

Signed-off-by: Wolfgang Mauerer <wolfgang.mauerer@siemens.com>
Parallelise time stamp acquisition

For large mail corpora, determining the time stamps can become
time consuming, to parallelise the operation.

Signed-off-by: Wolfgang Mauerer <wolfgang.mauerer@siemens.com>
Fix author name normalisation for parallel processing

Normalising author names requires access to the database,
and we need to ensure that the thread-specific conf object
is used as usual.

Signed-off-by: Wolfgang Mauerer <wolfgang.mauerer@siemens.com>
Clarify/fix some comments in the mailing list analysis

While at it, also move some currently unused code
to a non-executed section.

Signed-off-by: Wolfgang Mauerer <wolfgang.mauerer@siemens.com>
Do not rely on fixed directories for performance measurements

The performance measurement scripts failed to make some
directories configurable, but assumed hard-coded defaults
instead. Fix this, and also add some documentation on the
meaning of parameters.

Signed-off-by: Wolfgang Mauerer <wolfgang.mauerer@siemens.com>