add a few unit tests for QSObject
additional URL and e-mail tests
add unit tests for file objects
add tests for combined objects
ignoring pasteboard data for specific apps is handled by the clipboard plugin
Allow icons to be set for objects without handlers

Simply setting an icon in QSTypeDefinitions (Info.plist) will give an object an icon now
Various improvements to handling pasteboard objects

* Give all pasteboard objects IDs
* Put the object pasteboard type in the details
* Add a few new types (RTF)
* Fix up icons for images
* Add the source app name for unknown data objects
* Avoid just naming some objects @"Text"
define an image and name for RTF text
typo
move getting icon from QSTypeDefinitions to -[QSObject icon]
Add more internal commands for opening prefs. Fixes #1448
resolve aliases when browsing in the 3rd pane (by type)
consider resolved aliases in more places
Don't unload icons for objects who's icon never changes
Merge pull request #1488 from pjrobertson/retainIcons

Don't unload icons for objects who's icon never changes
set initial file icons based only on type

Calling `iconForFile:` causes the file's attributes to be read from disk, which could be very slow in some cases, defeating the purpose of `setQuickIcon…`. Instead, we do it in `loadIcon…` which runs in the background.

fixes #1431
add quick icons for folders

They typically don't have an extension, so they need to be handled
separately.
update icons on the main thread

to avoid several attempting to update simultaneously
always call `selectObjectValue:` when the object changes

`setObjectValue:` is lacking some smarts for comparing objects and
managing observers. `selectObjectValue:` takes care of that, as well as
the two lines that were removed.
Better description for unknown types