DMN FEEL warn if en-dash is present as a character in expression

This is taken from the DMN spec :

(amount *rate/12) / (1 – (1 + rate/12)**-term)

however this would fail to parse correctly as the first subtraction sign is an "en-dash" (0x2013) and not a minus/hyphen sign (0x2D)

(amount *rate/12) / (1 – (1 + rate/12)**-term)
                       ^ 
(amount *rate/12) / (1 - (1 + rate/12)**-term)

while an "em-dash" is much more noticeable, this "en-dash" can be confused more easily, especially depending on the font used:

– en-dash                     
- minus, or hyphen (standard)
— em-dash (much more noticeable in the difference)

It is suggested for the parser/compile to emit a warning if the en-dash is used in an expression --or potentially if it's the last character in a viable alternative.

A good way to check for the behavior is to use the wrong expression above to exhibit the behavior when the en-dash is misplaced for a minus sign for a subtraction operation.