* startrefactoring the event system
* refactor: blockquotes, code blocks and links refactored
* refactor codeblock to new event system
* refactor subparser until ghcode to new events
* finish adating ghcodeblock to new event
* add headings to new events
* add image to event system
* add emphasisAndStrong to event system
* fix wrong event name in emphasisAndStrong onEnd event
* spanGamut and build
* showdown.helper.event refactored to showdown.Event
* partial
* add links
* add metadata
* add strikethrough and table
* build
* add underline
* add unescapeSpecialChars
* small refactoring
* remove old tables parser
* add lists
* add simple event trigger tests
* build
* fix browserstack
* fix browserstack
* remove testing for ie11 and bumped firefox min version to 45
* fixes and closes#920
* build
* chore(ci): update CI node version to match node supported versions
* chore(ci): appveyor only supports up to node 16.x
* chore(ci): travis CI is not longer free/working; remove it
* chore(ci): add git workflow to replace travisCI linux builds
* doc(readme): add back in a badge for linux CI
* chore(ci): add windows to CI
* chore(ci): remove appveyor in favor of github actions
* doc(readme): update info about node supportability
* update CI node versions to match node supported versions
* remove node 17.x on appveyor, it only supports up to node 16.x
* travis CI is not longer free/working; remove it in favor of github actions