Allow to use rgba colors that allow to fix transparent selection bug in Chrome

[jcubic]

I have idea for a new feature for jQuery Terminal

In #586 there was bug with PrismJS text selection, this in fact the problem that hex colors give transparent selection in chrome. Fixing prism will not be possible because all colors use hex and we need rgba(....., 0.99) to fix transparent bug.

The formatting should allow to use colors in rgba and hsl.

ref: https://developer.mozilla.org/en-US/docs/Web/CSS/color_value

also hex can be 4 or 8 hex values (including alpha channel). so It can be 3, 4, 6 or 8 values.

TODO

• code
• unit tests