Transcript builtins -- implement activation level configuration

[cipriancraciun]

Tasks

• implement "internal" transcript activation level configuration (i.e. the compiler, interpreter, etc.);
• implement "script" transcript activation level configuration (i.e. the user-code);

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Notes

In both cases the configuration should be done either:

• at compile time (via cfg! macro);
• at run-time via command-line arguments;
• at run-time via environment variables;
  • VONUVOLI_SCHEME_TRANSCRIPT_LEVEL for the interpreter;
  • VONUVOLI_SCHEME_SCRIPT_TRANSCRIPT_LEVEL for the script;