Feature/andre/doc update plugin dev tutorial

Closes #342 and #424

See merge request frama-c/frama-c!3890

[E-ACSL] add option --then-last to e-acsl-gcc.sh

See merge request frama-c/frama-c!3894

Bugfix: name conflict when a function with contract shares a name with a logic function

Closes e-acsl#204

See merge request frama-c/frama-c!3899

Feature/eva/ivette functions table

See merge request frama-c/frama-c!3884

[Variadic] Fix the references to calls in unspecified sequences

Closes #327

See merge request frama-c/frama-c!3886

Fix handling of explicit cast to _Bool

Closes #2623

See merge request frama-c/frama-c!3897

Ast_info should return a value for integer constant expressions

Closes #2625

See merge request frama-c/frama-c!3893

- Cabs2cil.is_boolean_result returns true if the expression is of type _Bool
- use standard result instead of custom expression for cast of a boolean to _Bool

and update is_null_expr and is_non_null_expr in a similar manner as the other ones

The name seems to imply that it will return Some for any constant integer expression,
not only for integer literals

A fixe for Git versions < 2.22

See merge request frama-c/frama-c!3892