Refactor OakHTMLOutputView
Open new window for HTML output links with target="_blank"

Since switching to ARC we need to ensure the NSWindow is “over-retained” as we rely on “setReleasedWhenClosed:YES”.

Also add ability to close such windows from JavaScript.
Add debug output to WebView delegate
Find in folder window’s title could switch to “Untitled”

This is because we are using an NSDocument to perform the folder searching (as that’s a decoupled way to have the window indicate “unsaved changes” and present a warning sheet).

The downside is that by using an NSDocument we get some undesired implicit behavior, like automatically changing the window title or trying to re-open the “document” after relaunch.
Indicate that find window is not restorable

Since we are using it with an NSDocument, it defaults to use NSDocumentController as restoration class, which gives a warning during launch, if the find window was open during termination, and the conditions are so that the system wants to restore windows from last session.

Also indicate that we do not want to save drafts, unsure if this has any effect.
Make the preferences window restorable

This is not overly useful but the code serves as copy/paste for future endeavors into restoring non-document windows.

The feature requires that “Close windows when quitting an application” is disabled in System Preferences → General (I think that option is enabled by default, at least on 10.9).
Add comment to explain workaround for presumed WebKit bug

Since the code was written before open sourcing TextMate, the explanation was only to be found in a private commit log.
Use (custom) block based API for showing sheet
Refactor HTMLOutputWindow: Use properties and argument free init
Do not re-use busy HTML output views/windows

Additionally, we only re-use a window when the command is the same as what was last associated with the window. So doing a documentation lookup and then building the project will not re-use the (non-busy) documentation window for the build progress.

Closes #733