Remove outdated files
Remove another outdated file
Use correct function to show error
Mention inheritance for Echo.GUI.Modal
Remove useless docs for API classes
Subclasses info to be shown only on mouseover
Added disabling Pinboard plugin in Quirks Mode
Revert "Added function Echo.Utils.isQuirksMode + tests"

This reverts commit 41666f3b5574e4a60ea17be9a3fae7673599725b.