make nix attributes in default.nix extensible

See merge request frama-c/frama-c!3104

[Eva] Fix a bug where added annotations were always slevel annotations

See merge request frama-c/frama-c!3132

[Eva] Improves the heuristic for automatic loop unrolling — episode 2

Closes Value/Value#135

See merge request frama-c/frama-c!2943

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.

Simplifies the bug report gitlab template.

See merge request frama-c/frama-c!3121

[script] Fix exit code of `check_newline.sh`

See merge request frama-c/frama-c!3127

If the script find some errors, then the exit code is 1 instead of 0.

[Eva] The engines evaluates the location of ACSL \from clauses.

See merge request frama-c/frama-c!3109

If an lvalue [lv1] from a loop exit condition is always assigned to the value of
another lvalue [lv2] in the loop body, then the heuristic uses [lv2] as loop
variant instead of [lv1].
This commit ensures that this replacement is only done if [lv1] is assigned
to the value [lv2] in all possible path of the loop body.

- The automatic loop unrolling now supports non-natural loops.
- Improves the precision of the computation of delta increment.

Domains can then use these locations.
By lack of a cooperative evaluation engine of ACSL terms, only the cvalue domain
is used to evaluate terms of \from clauses into locations.

Resolve "Specs des fonctions flottantes (math.h)"

Closes #426

See merge request frama-c/frama-c!2405

[eacsl] Fix address of end segment in RTL layout

See merge request frama-c/frama-c!2979

[bin/analysis-scripts] improve shell scripts thanks to shellcheck

See merge request frama-c/frama-c!3106

[tests] fixes test directives in two tests about save/load

Closes #1036

See merge request frama-c/frama-c!3120