i18n icons

Graphics (*.ai, *.png, *.svg)
* Took a pass on all images making them sharper and clearer
* Renamed bold and italic to bold-b and bold-a
* Added bold-f, italic-k, bold-a and italic-a
* Reorganized illustrator file

ve.ui.Icons-raster.css, ve.ui.Icons-vector.css
* Added classes for new icons
* Appended bullet, number, indent and outdent class names with "list"

ve.ui.*ButtonTool.js
* Added definitions for static icon property
* For bold and italic, added i18n style definitions

ve.ui.ButtonTool.js
* Switched from re-using the name property (which is intended to be the symbolic name of the tool used when registering with the tool factory) to using an static icon property for defining the icon

Change-Id: I43e7c35835a1e6dfb06f2a70226fac0d395008e8
Merge "i18n icons"