Solving overflows! about muparserx HOT 8 CLOSED

Overflows will be fighted on per-operator/function basis.

Started with safe factorial postfix operator.

Thinking about something similar to this:

http://stackoverflow.com/questions/199333/best-way-to-detect-integer-overflow-in
-c-c

added initial overflow detection for "<<".

somewhat related: I changed the code to allow passing of ecDOMAIN_ERROR and 
ecOVERFLOW without converting it to ecEVAL.

There is no real problem with overflows in general. IEEE-754 will properly 
translate overflows to nan respectively +/-inf. For instance: 10^1234 will 
yield +inf which is exactly what i would expect. Similar results for 
1/(insanely small value). The only issue i found so far is that muparserx does 
not interpret insanely high values like "1e1234" properly. This should be fixed 
though but apart from this ther is no problem with relying on the mechanism 
provided by IEEE-754.

The only remaining issue (incorrect parsing of "1e1234" or "1e-1234") are 
resolved now.