… for the serialization/deserialization of the job and opcode status.

Job status 'gone' was not actually used. It can be reintroduced if
needed.

These are not comprehensive, but at least we have a start.

QuickCheck's batch driver (at least v1) doesn't show the test aborts,
but simply discards the specific exception and increases the abort
count. This makes it hard to debug the tests, so we modify our own test
wrapper (which so far only tracked total failures) to show any
exceptions.

The tests are moved to a separate data structure, and we can select a
subset of tests to run.

The patch adds some simple unit-tests for both the allocation function
(we can allocate small instances on an empty cluster, we can allocate in
tiered more starting from any size) and the balancing functions (one
single instance is placed optimally, a full cluster plus an empty node
can be rebalanced). The coverage has increased greatly, since this is
the bulk of the algorithm/code.

Also, the cluster tests are now being run with different options, since
they are much slower.

First, we reduce the max size of the disks, since Int on 32bits will
overflow for big simulated clusters. This is a real issue, that will
need fixing in real life, but for now we just "silence" this test.

Second, we increase the amount of time a test is allowed to run,
otherwise on slower computers some tests might time-out.

This makes (for now) the code hlint-clean. This is per se not a huge
gain, but it allows easier tracking of regressions in style later
(one-two new violations are easier to diagnose when not hidden among 20
“known” ones).

Test.QuickCheck.Batch.runTests doesn't return any error statistics,
which makes the test suite just display errorrs and always exit with
exit code 0. This is not good, since one cannot then actually batch run
tests.

This patch adds a wrapper over Batch.run which also modifies a passed
IORef Int to keep track of how many test failures or test aborts we had.
This makes it easy then to exit with an appropriate exit code.

This include instance text load tests.

This patch makes sure that all references to the name of the software is
ganeti-htools, not simply htools.

This doc-patch adds copyright and license information to (hopefully) all
needed files.

This patch moves the test declaration into QC.hs, so that test.hs has to
be modified only when we add a new test category.

This is more of an exercise in QuickCheck than strong testing.

This patch adds a QuickCheck-based test infrastructure and initial tests
based on it. The PeerMap module has a 100% coverage ☺️

Side-note: one has to read the source of QuickCheck to see how to use it
(especially the Batch submodule), the docs are not enough…