Feature Request - Dropdown sheet menu

(from [7ae50c2e936ca3a3edcac84c9e5dcc7b489d431d]) Initial implementation of icons for menus...adds icon to YUI Top Nav menu if available/attached [#663 Feature Request - Dropdown sheet menu] https://github.com/exponentcms/exponent-cms/commit/7ae50c2e936ca3a3...

(from [c4d62bc5ade706bb0fa57581f448cbfee43b3dc2]) Initial implementation of a Dropdown sheet (mega?) menu (iOS compatible?), probably needs a lot more work, recommend turning 'chrome' on to set the number of columns wide or defaults to 3...uses this sample http://net.tutsplus.com/tutorials/html-css-techniques/how-to-build-... [#663 Feature Request - Dropdown sheet menu] https://github.com/exponentcms/exponent-cms/commit/c4d62bc5ade706bb...

(from [ebde25e58bdf116175bf1fee651140b43d9cd9ce]) Adds optional setting for page description and hover menu item effect, close ticket #322 Create iOS friendly navigation menu view since this menu is iOS friendly [#663 Feature Request - Dropdown sheet menu] [#322 Create iOS friendly navigation menu view state:resolved responsible:dleffler milestone:2.1.0] https://github.com/exponentcms/exponent-cms/commit/ebde25e58bdf1161...

(from [e522ddfd8303d34e2a0dc99a515ad232143b79a1]) Should make the new mega menu able to replicate referenced mega menu in ticket....not very flexible for menu hierarchies over 3 levels deep (parent->child->grandchild). two basic dropdowns, the 2 level dropdown where all items are similar, and the 3 level dropdown which groups grandchild items under the child item. [#663 Feature Request - Dropdown sheet menu] https://github.com/exponentcms/exponent-cms/commit/e522ddfd8303d34e...

(from [66badcbf92a8b87b468a4cff89771f2f1c11dfe3]) Minor tweaks to mega menu style [#663 Feature Request - Dropdown sheet menu] https://github.com/exponentcms/exponent-cms/commit/66badcbf92a8b87b...

(from [53862ae16e64d4b2f6d10e1b36d8b0a640f407d3]) Minor tweaks to mega menu style to better allow for NOT displaying description [#663 Feature Request - Dropdown sheet menu] https://github.com/exponentcms/exponent-cms/commit/53862ae16e64d4b2...