Initialize the quick help plugin even if the plugin fails to swizzle a method.

The other swizzling might succeed.
Open all doc links in Dash.

This adds the ability to intercept option-double-clicks on symbols,
as well as to open "quick help autocomplete" links.

This feature can be disabled, like the rest of Dash, by selecting the "Disabled"
menu item within the "Dash Integration" submenu of Xcode's "Edit" menu.
Merge pull request #18 from wearhere/jeff/open_all_doc_links

Open all doc links in Dash.