Faust passes invalid --class-name and --super-class-name identifiers to generated code

[Pri-yan-shu]

Faust doesn't correctly modify --class-name and --super-class-name to valid c++ identifiers and generates uncompilable c++ code. Its bigger issue with faust2.. scripts using filename as classname, for instance faust2lv2, so filenames that are valid (for instance starting with a digit or containing hyphen) result in error during the compilation of the generated c++ code.