[bug-libmatheval] Improvements suggestions

[Darkounet]

Hi  guys !

I've been doing some work around libmatheval for a while (in order to 
include it in one of my projects). I've managed to add some little 
features, which are the following :

	* Removed dependencies on @LEXLIB@ (-ll or lfl), because there is no 
need to have yywrap function in libmatheval.
	* Added the `evaluator' prefix to every symbols in LEX/YACC generated 
files (this is pseudo standard, POSIX does not define -P option for LEX, 
but it is implemented in almost any LEX implementation).
	* Added the evaluator_evaluate2, a function that I described in a 
previous message on this list.
	* The test suite for guile is now optional (I did not dropped it, this 
was necessary since compatibility errors with newer versions of guile 
have been reported

I also changed the version number (in order to fit with my project's 
main binary version number).

Quite a long time ago, I've requested to join the developer groups on 
savannah, but I did not get any response. I hope the project is not died 
anyway.

For those who want the fixes, I join the diff with the mail.

Regards,
Romain