Liberty: Fix bit_... fields in bus definitions

[ubfx]

The Liberty User Guide specifies these fields to be integers, but they are currently given as floats in the .lib-files, leading to problems with some tools.

Example before fix:

type ("bus8") {
        base_type : "array";
        bit_from : 7.0000000000;
        bit_to : 0.0000000000;
        bit_width :  8.000000000;
[...]

Fix #6

[ubfx]

I also checked all other logic libraries, and this (hdll) seems to be the only one where this is a problem. All others are already using integers.

[RTimothyEdwards]

I can work on this after I merge the pull request for the cut layer issue, unless you have a pull request for this waiting.

[RTimothyEdwards]

Sorry, I see the pull request. Somehow until I refreshed my browser I didn't see any files changed. So I'll go ahead and review.

[RTimothyEdwards]

All looks good to me.