Copy `entryContents` before adding it to an array

Avoid the chance that the object will be released before being added to the array.

You knew that we hadn't actually fixed the catalog scanning crashes, right? ;-)

This fix is in relation to the following crash report:
I recently put a lock on `entryContents`, so I'm pretty sure that this crash is **unrelated** to threading problems in the `reloadSets` method (yes, I did just say that!)
If you look at thread 9, you'll see that the mutex lock (presumably on `catalog`) is working.

What I think the problem here is, is that `entryContents` must sill be getting modified somewhere before it's added to the array (released, most likely). I've taken what you could perhaps call a shortcut in avoiding any threading problems and just copying the object.

Note: This pull request is against release. We need to get another release build out anyway so that we can put new localisation stuff in

```
Process:         Quicksilver [20455]
Path:            /Applications/Quicksilver.app/Contents/MacOS/Quicksilver
Identifier:      com.blacktree.Quicksilver
Version:         ß71 (3937)
Code Type:       X86-64 (Native)
Parent Process:  ??? [1]

Date/Time:       2012-12-11 23:57:44.798 +0100
OS Version:      Mac OS X 10.7.5 (11G63)
Report Version:  9

Crashed Thread:  0  Dispatch queue: QSPresetRecentApplications106

Exception Type:  EXC_BAD_ACCESS (SIGSEGV)
Exception Codes: 0x000000000000000d, 0x0000000000000000

VM Regions Near 0:
--> 
    __TEXT                 0000000100000000-0000000100031000 [  196K] r-x/rwx SM=COW  /Applications/Quicksilver.app/Contents/MacOS/Quicksilver

Application Specific Information:
objc[20455]: garbage collection is OFF

Thread 0 Crashed:: Dispatch queue: QSPresetRecentApplications106
0   com.apple.CoreFoundation      	0x00007fff8ef1642c CFHash + 332
1   com.apple.CoreFoundation      	0x00007fff8ef1f605 CFBasicHashAddValue + 1573
2   com.apple.CoreFoundation      	0x00007fff8ef879a1 -[NSMutableSet addObjectsFromArray:] + 513
3   com.blacktree.QSCore          	0x00000001000dc9d4 -[QSLibrarian reloadSets:] + 323
4   com.apple.Foundation          	0x00007fff86fedd0e __-[NSNotificationCenter addObserver:selector:name:object:]_block_invoke_1 + 47
5   com.apple.CoreFoundation      	0x00007fff8ef577ba _CFXNotificationPost + 2634
6   com.apple.Foundation          	0x00007fff86fd9fc3 -[NSNotificationCenter postNotificationName:object:userInfo:] + 65
7   com.blacktree.QSCore          	0x00000001000d51b5 __30-[QSCatalogEntry scanAndCache]_block_invoke_0 + 359
8   libdispatch.dylib             	0x00007fff8a86bc75 _dispatch_barrier_sync_f_invoke + 33
9   com.blacktree.QSCore          	0x00000001000d4ffe -[QSCatalogEntry scanAndCache] + 181
10  com.blacktree.QSCore          	0x00000001000d5525 -[QSCatalogEntry scanForced:] + 756
11  com.apple.Foundation          	0x00007fff86fedd0e __-[NSNotificationCenter addObserver:selector:name:object:]_block_invoke_1 + 47
12  com.apple.CoreFoundation      	0x00007fff8ef577ba _CFXNotificationPost + 2634
13  com.apple.Foundation          	0x00007fff86fd9fc3 -[NSNotificationCenter postNotificationName:object:userInfo:] + 65
14  com.blacktree.QSCore          	0x00000001000feeda __26-[VDKQueue watcherThread:]_block_invoke_0 + 223
15  libdispatch.dylib             	0x00007fff8a869a82 _dispatch_call_block_and_release + 18
16  libdispatch.dylib             	0x00007fff8a86b8f2 _dispatch_main_queue_callback_4CF + 308
17  com.apple.CoreFoundation      	0x00007fff8ef43e7c __CFRunLoopRun + 1724
18  com.apple.CoreFoundation      	0x00007fff8ef43486 CFRunLoopRunSpecific + 230
19  com.apple.HIToolbox           	0x00007fff866a72bf RunCurrentEventLoopInMode + 277
20  com.apple.HIToolbox           	0x00007fff866ae4bf ReceiveNextEventCommon + 181
21  com.apple.HIToolbox           	0x00007fff866ae3fa BlockUntilNextEventMatchingListInMode + 62
22  com.apple.AppKit              	0x00007fff874be779 _DPSNextEvent + 659
23  com.apple.AppKit              	0x00007fff874be07d -[NSApplication nextEventMatchingMask:untilDate:inMode:dequeue:] + 135
24  com.apple.AppKit              	0x00007fff874ba9b9 -[NSApplication run] + 470
25  com.apple.AppKit              	0x00007fff87736eac NSApplicationMain + 867
26  com.blacktree.Quicksilver     	0x0000000100002224 0x100000000 + 8740

...

Thread 8:: Dispatch queue: QSPresetQSCatalogEntries
0   libsystem_kernel.dylib        	0x00007fff88b41bf2 __psynch_mutexwait + 10
1   libsystem_c.dylib             	0x00007fff846a31a1 pthread_mutex_lock + 545
2   com.blacktree.QSCore          	0x00000001000dc8ef -[QSLibrarian reloadSets:] + 94
3   com.apple.Foundation          	0x00007fff86fedd0e __-[NSNotificationCenter addObserver:selector:name:object:]_block_invoke_1 + 47
4   com.apple.CoreFoundation      	0x00007fff8ef577ba _CFXNotificationPost + 2634
5   com.apple.Foundation          	0x00007fff86fd9fc3 -[NSNotificationCenter postNotificationName:object:userInfo:] + 65
6   com.blacktree.QSCore          	0x00000001000d51b5 __30-[QSCatalogEntry scanAndCache]_block_invoke_0 + 359
7   libdispatch.dylib             	0x00007fff8a86bc75 _dispatch_barrier_sync_f_invoke + 33
8   com.blacktree.QSCore          	0x00000001000d4ffe -[QSCatalogEntry scanAndCache] + 181
9   com.blacktree.QSCore          	0x00000001000dd94a -[QSLibrarian loadMissingIndexes] + 245
10  com.blacktree.Quicksilver     	0x000000010000830a 0x100000000 + 33546
11  com.apple.Foundation          	0x00007fff8703172a -[NSThread main] + 68
12  com.apple.Foundation          	0x00007fff870316a2 __NSThread__main__ + 1575
13  libsystem_c.dylib             	0x00007fff846a48bf _pthread_start + 335
14  libsystem_c.dylib             	0x00007fff846a7b75 thread_start + 13

Thread 0 crashed with X86 Thread State (64-bit):
  rax: 0x0000000000000000  rbx: 0xb0000000105783c0  rcx: 0x00007fff74cdade8  rdx: 0xb0000000105783c0
  rdi: 0xb0000000105783c0  rsi: 0xb0000000105783c0  rbp: 0x00007fff5fbfdf00  rsp: 0x00007fff5fbfdee0
   r8: 0x0000000000000000   r9: 0x0000000000000004  r10: 0x0000000100235030  r11: 0x00000001002101d8
  r12: 0x0000000000000048  r13: 0x0000000000000001  r14: 0x0000000000000000  r15: 0x00007fff74cd9520
  rip: 0x00007fff8ef1642c  rfl: 0x0000000000010246  cr2: 0x000000015de3f000
Logical CPU: 2
```