fractions in arbitrary values

• Handle Fractions in Arbitrary Values: Now, you can use fractions in most spacing properties such as margins, widths, heights, padding, etc. For example, you can set the width and height of an element like this: w-(1/7) h-(4/7) or its margins like this: mx-(1/9).
• Add --prefix Option to the build-fonts Command: Apply the style's filename as the prefix in icon fonts for both the fonts.tss and purgetss.fonts.js files.