optional legacy support

• legacy-support is now optional

You can remove the inline-block fallback from the compiled css by setting the variable legacy-support to false in the variables file. This is set to true by default.

• fixed -ms-flex-line-pack usage to use the correct syntax for those browsers that used microsoft's custom implementation of the flexbox spec (ie < 11)

• removed duplication of some css properties due to incorrect use of guarded mixins in less and if statements in scss

• sets precision of compiled css to 8 decimal places