New alignment setting

Changes

• BREAKING - added alignment feature. Instead of positioning via hint-top, you must now also specify the alignment of the tooltip. To fix any preexisting, broken hints, just add -middle to your positioning attribute. So if you had hint-bottom, changing it to hint-bottom-middle will fix it. See docs for details .
• improved customizability of simple hint. Can now edit sass variables and run npm run build to create simple-hint library with your own settings