Faulty compiler: new CodeError class

[privat]

This PR adds a new error super class for syntactic and semantic errors: CodeError.

The changes are rather brutal since:

• SyntaxErrorNotification become an Error (instead of a notification). The name stays unchanged for now.
• OCSemanticError is stripped of its responsibility to report error on the UI (yes, it was this bad).

Note: OCSemanticWarning, especially OCUndeclaredVariableWarning are let untouched (yet!)

Let's see if CI thinks this to too much change to handle...

[privat]

tests are ok, except windows. But I added more commits for some related cleanup