Only one split (either static or dynamic) can be active on the same term.
If a new split is encountered while a split is aleady active on the same term,
the old split is removed.

When two loops follow each other, the automatic loop unrolling is performed on
the transition edge between the two, where the current statement (from
Cil.CurrentLoc) is still the first loop.

Adds a test for this case.

This reverts commit e9c60779

For abstract domains, the valuation is now a record of three functions:
[find], [fold] and [find_loc].

Adds a function in the evaluation engine to convert Valuation maps into
these records.

Prerequisite for new options or annotations to configure more finely
the subdivisions.
In partition.ml, the subdivisions are disabled.
Other files always use the default value of subdivisions.

The new option -eva-auto-loop-unroll defines the maximum limit of automatic
loop unrolling.

These module definitions were previously in abstract_value, abstract_location
and abstract_domain. They are now grouped in this new file for the three
abstractions.
These module types should only be useful for the engine, and need not to be
visible in the implementation of the various abstractions.

New module type Leaf in abstract_value, abstract_location and abstract_domain
with the key identifying the module. The internal structure is no longer needed
in these abstractions, and is instead built by the engine from this key.

Keys are no longer exported outside the modules.
For abstract domains, the key is automatically created by the functor
Domain_builder.Complete from the domain name.

Many changes throughout the analyzer:
- in the engine, Abstract_value.{Internal|External} becomes
  Abstract.Value.{Internal|External}.
- in the abstractions, Abstract_value.Internal becomes Abstract_value.Leaf.

       Add migration script

And not at each application of the split action.

join_duplicate_keys replaces the code `of_partition (to_partition)` in
trace_partitioning, and is probably more efficient.
filter_map is applied to flows instead of partitions.

Creates stamps according to the evaluation of the returned expression in states.

Moves function split_by_evaluation from evaluation to partition.
Moves function split_final_state from transfer_stmt to partition.
New partitioning action Restrict, that restricts the rationing according to the
evaluation of an expression into some expected values.

split_monitors are created and internally used by partition.
New type split_kind to distinguish between static and dynamic splits, instead
of using different constructors in the action type.