Full support of non-integer exponents in all sass variations

[strarsis]

This PR will add eyeglass-math as package dependency (for eyeglass users),
a feature detection for pow() supporting non-integer exponents
and a pow() polyfill that supports non-integer exponents.

eyeglass users can install modularscale-sass package as usual, no further intervention required,
pow() (so modularscale) will work with non-integer exponents nicely and very fast
(using eyeglass-math pow native javascript function).

plain libsass users and users of ruby sass without compass can also enjoy non-integer exponents
as the polyfill is used automatically, also no further intervention required, performance shouldn't be different.

With best regards

[scottkellum]

@strarsis Thanks for your work on this. 3.0 will allow you to plug in 3rd party pow() without cluttering up this codebase with supporting it.

Again, thanks for the work this is great but decluttering the codebase is a priority moving forward.

[strarsis]

This is good news as I use libsass + eyeglass primarily now.
Can I install 3.0 already, would the 3x branch of this repository enough?

[scottkellum]

@strarsis It’s not really packaged up for distribution but you can absolutely use it. Docs are written and stylesheets are here.