More snippets support

Element tags from https://developer.mozilla.org/en-US/docs/Web/Guide/HTML/HTML5/HTML5_element_list

Edited in Textmate 2 but I found it's not possible to put them into a submenu like Insert Tag. Then I copied them to Textmate 1 and reordered them into submenu, but it became incompatible with version 2, any idea?