Feature/eva/trace partitioning

See merge request frama-c/frama-c!1966

[Kernel] make yojson a mandatory dependence

See merge request frama-c/frama-c!2122

[ACSL] fixes parsing issues about C fields

See merge request frama-c/frama-c!2226

[Kernel] Fixes Cil.constFold on expressions whose size is not 32 bits.

Closes #640

See merge request frama-c/frama-c!2231

Uses the operand equal to 0, instead of creating a new 0 expression which may
have an incorrect type.

Fixes a bug when splitting on a value, as we compare the result of an evaluation
with the value given by inject_int.

[Eva] The bitwise offsm_value returns `Bottom when reducing the cvalue to bottom.

Closes #639

See merge request frama-c/frama-c!2230

Fixes a crash in cvalue_forward, where values are assumed to be non bottom.

Restores a previous optimization.
This is a useful optimization, as the inclusion tests between incoming states
and already propagated states are very costly.

[OPAM] allows the use of the package alt-ergo-free as an alternative to alt-ergo

Closes #635

See merge request frama-c/frama-c!2228

And not at each application of the split action.

Slightly simplifies the widening.

Removes state_partitioning.mli.
Since there is only one implementation of state_partitioning signature, there is
no need to keep this separate file.

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.