Indentation, escaping, code improvements

:+1: Thanks for doing the entire file, I like this plugin much more now.

You are messing with the indentations. You mix up tabs with spaces ... maybe has to do with other people working with this as well with other editor settings. Seems to get especially messy when you copy things arroung. I saw that you copyed my other function manually over and there are some huge indents.

I personally prefer real tabs but converted everything to just 2 space indentations since this seems to be the most used here.

There are this universal setting files, bootstrap has one, that some editors read and use. Maybe this should be added here as well. There you basically say "This project uses 2 spaces as tabs" ...

I put the enqueue function inside the class.

I also added 'icon-white' shortcode so people get that they expect but left 'icon_white' for backwards compatibility.

Please let me know if you like my input, I would like pushing this plugin forward.