Aligning to WikimediaUI style guide by replacing colors with
standard color palette equivalents, merging close colors
(ex: `#E6E6E6` & `#eee` become `#eaecf0` ) and slightly increase
contrast on a few to meet WCAG 2.0 level AA criteria.
Also:
- following other code bases like MobileFrontend or OOjs UI in
using `border-radius` property instead of obsolete mixin
- removing non-existing browser vendor prefixes in mixins
- removing non-used Less variables
- bringing CSS/Less code closer to coding standards and
- simplifying Less code where applicable
Change-Id: Icb936e14ff613471ea1da6df6341ec1b0543cfaf
Also do a bunch of refactoring to:
* keep LESS rules in more sane locations so it is not as hard to get an overview
(most of the metadata panel rules were in mmv.less)
* move mmv.mixins.less up one directory as it is not specific to the UI
* move the SVG icons as all of them were related to the UI
* remove the marging-right hack which was used to keep the title text from
overflowing the button; instead use a float and overflow properties to make
sure text that is too long gets hidden
Change-Id: Icc8ea2e766be67d86ae98c734721b2185bd6c36e