Fix docs and preferences to indicate non-CoreText renderer is deprecated

Now that CoreText scrolling performance is fixed with the stateful
renderer we should eventually stop supporting the legacy NSTextView
renderer which doesn't renderer properly and cannot do proper
fixed-width column rendering that Vim uses. Mark it as deprecated for
now but it will be removed in the future.

runtime/doc/gui_mac.txt

@@ -257,6 +257,7 @@ KEY				VALUE ~
 *MMLoginShellArgument*		login shell parameter [string]
 *MMLoginShellCommand*		which shell to use to launch Vim [string]
 *MMNoFontSubstitution*		disable automatic font substitution [bool]
+				(Deprecated: Non-CoreText renderer only)
 *MMNoTitleBarWindow*		hide title bar [bool]
 *MMTitlebarAppearsTransparent*	enable a transparent titlebar [bool]
 *MMAppearanceModeSelection*	dark mode selection (|macvim-dark-mode|)[bool]
@@ -793,9 +794,6 @@ if you would like to see certain messages localized.
 This list is by no means exhaustive, it only enumerates some of the more
 prominent bugs/missing features.
 
-- Under macOS Mojave (10.14), the default renderer (Core Text renderer) has
-  some performance issues and scrolling is not as smooth as previous macOS
-  versions (10.13 or below).
 - Sound.  MacVim does not currently support |+sound| yet.
 - |modifyOtherKeys| support.  This feature allows for more granular key
   mapping (e.g. differentiating <C-I> and <Tab>) and isn't supported by the

src/MacVim/Base.lproj/Preferences.xib

@@ -367,9 +367,8 @@
                 <textField verticalHuggingPriority="750" horizontalCompressionResistancePriority="250" fixedFrame="YES" id="815">
                     <rect key="frame" x="17" y="252" width="449" height="28"/>
                     <autoresizingMask key="autoresizingMask" flexibleMaxX="YES" flexibleMinY="YES"/>
-                    <textFieldCell key="cell" controlSize="small" sendsActionOnEndEditing="YES" id="991">
+                    <textFieldCell key="cell" controlSize="small" sendsActionOnEndEditing="YES" title="(Deprecated) Deselect this option to use the legacy renderer, which is unsupported and will be removed in a future version." id="991">
                         <font key="font" metaFont="smallSystem"/>
-                        <string key="title">Selecting this option will increase rendering performance but double-tapping with three fingers to look up words will no longer work.</string>
                         <color key="textColor" white="0.5" alpha="1" colorSpace="calibratedWhite"/>
                         <color key="backgroundColor" name="controlColor" catalog="System" colorSpace="catalog"/>
                     </textFieldCell>

src/MacVim/MacVim.h

@@ -348,7 +348,7 @@ extern NSString *MMShareFindPboardKey;
 
 extern NSString *MMAutosaveRowsKey;
 extern NSString *MMAutosaveColumnsKey;
-extern NSString *MMRendererKey;
+extern NSString *MMRendererKey; // Deprecated: Non-CoreText renderer
 
 enum {
     MMRendererDefault = 0,

src/MacVim/Miscellaneous.h

@@ -32,7 +32,7 @@ extern NSString *MMBaselineOffsetKey;
 extern NSString *MMTranslateCtrlClickKey;
 extern NSString *MMTopLeftPointKey;
 extern NSString *MMOpenInCurrentWindowKey;
-extern NSString *MMNoFontSubstitutionKey;
+extern NSString *MMNoFontSubstitutionKey; // Deprecated: Non-CoreText renderer
 extern NSString *MMAppearanceModeSelectionKey;
 extern NSString *MMNoTitleBarWindowKey;
 extern NSString *MMTitlebarAppearsTransparentKey;