Converts a module path on the form "Foo.pmod/Bar.pmod" or
"/path/to/pike/lib/modules/Foo.pmod/Bar.pmod" to a module
identifier on the form "Foo.Bar".
If module_prefix or module_suffix are given, they are
prepended and appended, respectively, to the returned string if
it's a module file (i.e. ends with ".pmod" or
".so"). If object_suffix is given, it's appended to the
returned string if it's an object file (i.e. ends with
".pike").