mpz_set_str should be restrictive

[John Malecki]

I do not want "3 14" to mean 314.  I would like the conversion
function to be as strict as possible -- no spaces allowed anywhere.

     It turns out that it is not entirely true that this function
     ignores white-space.  It does ignore it between digits, but not
     after a minus sign or within or after "0x".  We are considering
     changing the definition of this function, making it fail when
     there is any white-space in the input, since that makes a lot of
     sense.  Send your opinion of this change to <address@hidden>.  Do
     you really want it to accept "3 14" as meaning 314 as it does now?