Fix for monitors with long-decimal refresh rates

[nickcooked]

My monitor is some cheap imported thing I got years ago. It has display resolutions like:

2560 x 1440 @94.87503052Hz
2560 x 1440 @75.00001526Hz
1280 x 720 @59.87503052Hz

(this was printed post-change)

Basically, there was no way to set certain resolutions because 95/94/94.5 were not accepted by the match tolerance of 0.005. And the previous d option did not display the true decimal value to try to get a better match. So I changed both.

d will print the actual precise reported Hz. Trailing zeroes are stripped including the decimal if all zeroes. MatchesRefreshRate was relaxed.

Now this command actually works like I'd expect it to.

displaymode t 2560 1440 @94.87503052 0

Oh, and added a release build command to readme. Feel free to remove that.

[nickcooked]

btw thanks for the utility!