Removed dealloc method that did nothing but nil an ivar

Doing so is not needed, and removing this is a small step to converting to ARC.
Use delegate getter method, mark all ivars as @private

Removed a few direct uses of _delegate ivar in favour of [self delegate].
This then allowed me to mark all ivars as @private.
Renamed two ivars to match their methods; changed nib to xib

Renamed _maxClickTimeDifference ivar to _maximumClickCountTimeDifference.
Renamed _simulateHoldEvents ivar to _simulateHoldEvent. (Note singular vs plural.)

This will help with eventually moving to auto-synthesize.

Used Xcode/IB 3.1.4 on OS 10.5 to convert the nib to xib; still deploys to OS X 10.5 and later.

Renamed binding in nib from simulateHoldEvents to simulateHoldEvent,
the binding was to the (previously misnamed) ivar, instead of the method,
probably broken when I added underscore prefixes to ivars.
Use @property and @synthesize

Use @property to declare a few things,
and use @synthesize a few thing.
No change to semantics/behaviour.
Simplify creation of string by using stringWithUTF8String
In preparation for delegates becoming weak in ARC use a strong stack variable as a temporary

Harmless under MRR and GC.
Made some private globals static; fixed trailing whitespace.
Fix warning about assignment in 'if' by adding extra parens
Added comment to clarify that return value must be deallocated by caller
Improved ARC compatibility by eliminating a bunch of toll free bridging

Instead, use CF APIs to accomplish the same thing.  CF APIs have the same
memory management rules in MRC, GC, and ARC.

These changes are more extensive than my previous changes, and so
the risk of regression is higher.
Reformat whitespace to improve readability.