Pause emulator when opening Pokes/Cheats

Until this fix the first time the user opened Pokes/Cheats in a
session the emulator kept running. Visible symptoms, in order of
how likely the user is to notice them:

* Memory Browser open, then Pokes/Cheats: closing Pokes/Cheats
  resumed the emulator with Memory Browser still on screen, and
  the browser's snapshot started drifting against live memory.

* Pokes/Cheats opened alone: z80 kept executing while the user
  enabled cheats, so a poke could be partially overwritten by the
  game's own code before it stuck.

* Once Pokes/Cheats had been opened and closed once, subsequent
  utility windows (Memory Browser, Rollback, etc.) stopped
  pausing the emulator — they opened normally but showed a live,
  drifting view instead of the expected snapshot. The defect
  persisted until the next app launch.

Root cause: PokeMemory.xib was the only utility xib without
visibleAtLaunch="NO" (the attribute defaults to YES when omitted).
PokeMemoryController.init touches [self window] to register a
close-notification observer, which lazy-loads the xib; with
visibleAtLaunch=YES, NSNib orders the window front during the
load. By the time showWindow: ran, isVisible was already YES, so
its early-return guard returned without calling pause. The close
block still called unpause unconditionally, walking the pause
counter down by one each cycle.

Adding visibleAtLaunch="NO" to PokeMemory.xib lines it up with
the other utility xibs. releasedWhenClosed="NO" is added for the
same consistency; NSWindowController already forces it at runtime.

Author: morozov

fusepb/xibs/PokeMemory.xib

@@ -14,7 +14,7 @@
         <customObject id="-1" userLabel="First Responder" customClass="FirstResponder"/>
         <customObject id="-3" userLabel="Application"/>
         <arrayController id="18" userLabel="Pokes"/>
-        <window title="POKEs/Cheats" allowsToolTipsWhenApplicationIsInactive="NO" autorecalculatesKeyViewLoop="NO" oneShot="NO" frameAutosaveName="PokeMemory" animationBehavior="default" id="1" userLabel="PokeMem" customClass="NSPanel">
+        <window title="POKEs/Cheats" allowsToolTipsWhenApplicationIsInactive="NO" autorecalculatesKeyViewLoop="NO" oneShot="NO" releasedWhenClosed="NO" visibleAtLaunch="NO" frameAutosaveName="PokeMemory" animationBehavior="default" id="1" userLabel="PokeMem" customClass="NSPanel">
             <windowStyleMask key="styleMask" titled="YES" closable="YES" miniaturizable="YES" resizable="YES"/>
             <windowPositionMask key="initialPositionMask" leftStrut="YES" rightStrut="YES" topStrut="YES" bottomStrut="YES"/>
             <rect key="contentRect" x="196" y="240" width="480" height="270"/>