2-complement signed hex number literals (INT#FFFF == -1?)

[riederm]

Should rusty be able to reprsent negative hex numbers as literals? #848 will not allow a line like this: x : INT := INT16#FFFF: in terms of the bit representation, 1111 1111 1111 1111 it is -1 since the declared type is a signed 16 bit integer. I guess it is the same for x: INT := INT2#1111_1111_1111_1111;