Dropped signed integer types support

Feature does not have real application. Only shifting but it is buggy
and too complicated in usage. In genera, not worth of support.
Removed hardcode of s64 in operations.

Now all operations are performed with default_intval_type type.
Force heigher-sized type if one of intvals in expression is heigher
than default.
Force heigher-sized internal type in case of long hex value.

For example with default type U32
0x11
will print:
Dec: 17
Hex: 0x00000011
Bin:
31     24  23     16
0000 0000  0000 0000
15      8  7       0
0000 0000  0001 0001
while 0x000000011:
Dec: 17
Hex: 0x0000000000000011
Bin:
63     56  55     48
0000 0000  0000 0000
47     40  39     32
0000 0000  0000 0000
31     24  23     16
0000 0000  0000 0000
15      8  7       0
0000 0000  0001 0001