deprecate boolean evaluation of floating point and character types

[Richard (Rikki) Andrew Cattermole]

Characters are quite often compared against zero when doing string 
handling in C without the binary expression. For this reason I would not 
want to see this changed.



Now floats on the other hand... there is no clear truthiness value 
associated with them, unless IEEE-754 defines one (it doesn't appear to 
for 2008 version).

C23 appears to not define if a floating point type can even convert to 
bool, although it does mention bool as not being supported in multiple 
places.