Update Eiffel definition

Hi,

This update enables a better fitting with [Standard ECMA-367](http://www.ecma-international.org/publications/standards/Ecma-367.htm) (Eiffel: Analysis, Design and Programming Language).

These changes are introduced:
- Disable comments into strings
- Enable concise form for real numbers
- Enable juxtaposed digit separators
- Check char and string content.