Truncate results and remove leading 0s

[timreyes]

See post below for original request:
https://discuss.saleae.com/t/simple-parallel-the-way-of-displaying-data/1996

When using 4bits, the data value doesn’t need to be 4 digit.
0x0 ~ 0xF are enough to show the data.
“0x000F, 0x0001, 0x0000” has too many character without any meaning.
Can you fix to display only valid data character /
0x? for 1~4bits,
0x?? for 0xoo00 ~ 0x00FF.

[tgtakaoka]

It would be nice if we can choose octal as radix as well.
Anyway the PR#17 is ready for review. Please have a look.