Fixed the display bug of .button-group on Chrome, should now display properly. Documented forms, inputs and checkboxes/radios, buttons, groups and mixins are coming.
Swapped prepros out for an Atom plugin, as prepros was getting a bit annoying with all those popups. `node-sass` is still used, but some parameters were changed. For all intents and purposes, this commit should most probably be ignored as nothing substantial was changed. The only thing that is a bit different is that the encoding at the start of both .min.css files is now removed. If this somehow ends up causing trouble, then DO refer to this commit in your issue, if you read this!
Hiding (normal and accessible) has been added via mixins in the utility_mixins file (utility module). Updated both mixins, along with the responsive padding and margin mixins to deal with incosistencies with four-step grid. The legacy grid system should now be fully supported in all 4 mixins in the utility module, making it easier to use them with four-step grids.
All @media queries now use the 'screen' mediatype, so that print stylesheets can be more easily implemented in the future, using small screen layouts, but not mobile-specific tricks.
Development environment has been Windows for months, just recently moved to UbuntuGnome 16.04 (LTS), so most of the files have been altered a little bit (line endings etc.). Similarly, my toolchain which was Atom (formerly SublimeText), SourceTree and Koala has been changed to Atom, GitKraken and Prepros, causing certain things to recompile and reconfigure based on said tools. New branch has been created under `dev211` to work on the next release `v2.1.1`.
