Refactor MacVim tests and add startup delayed full screen tests

Add test suite utility functions to set/restore defaults, adding/tearing
down a new Vim window, making temp files, wait for full screen
transition. This helps simplify per-test code and prevent mistakes.

Add new tests for delayed full screen on startup. This happens when a
vimrc/gvimrc sets 'fullscreen' on startup and MacVim has to delay
entering full screen until the window has been presented. This
incidentally regression tests a bug (fixed in macvim-dev#1521) where simply having
'set fuopt= fullscreen' in a gvimrc would cause MacVim to crash on
startup due to bad interaction with window resize messages.

src/MacVim/MMAppController.h

@@ -88,6 +88,7 @@
 - (void)refreshAllResizeConstraints;
 - (void)refreshAllTextViews;
 
+- (void)openNewWindow:(enum NewWindowMode)mode activate:(BOOL)activate extraArgs:(NSArray *)args;
 - (void)openNewWindow:(enum NewWindowMode)mode activate:(BOOL)activate;
 
 //

src/MacVim/MMAppController.m

@@ -1298,31 +1298,39 @@ - (BOOL)validateMenuItem:(NSMenuItem *)item
     return YES;
 }
 
-/// Open a new Vim window, potentially taking from cached (if preload is used).
-///
-/// @param mode Determine whether to use clean mode or not. Preload will only
-/// be used if using normal mode.
-///
-/// @param activate Activate the window after it's opened.
-- (void)openNewWindow:(enum NewWindowMode)mode activate:(BOOL)activate
+- (void)openNewWindow:(enum NewWindowMode)mode activate:(BOOL)activate extraArgs:(NSArray *)extraArgs
 {
     if (activate)
         [self activateWhenNextWindowOpens];
 
     // A cached controller requires no loading times and results in the new
     // window popping up instantaneously.  If the cache is empty it may take
     // 1-2 seconds to start a new Vim process.
-    MMVimController *vc = (mode == NewWindowNormal) ? [self takeVimControllerFromCache] : nil;
+    MMVimController *vc = (mode == NewWindowNormal && extraArgs == nil) ? [self takeVimControllerFromCache] : nil;
     if (vc) {
         [[vc backendProxy] acknowledgeConnection];
     } else {
         NSArray *args = (mode == NewWindowNormal) ? nil
             : (mode == NewWindowClean ? @[@"--clean"]
                                       : @[@"--clean", @"-u", @"NONE"]);
+        if (extraArgs != nil) {
+            args = [args arrayByAddingObjectsFromArray:extraArgs];
+        }
         [self launchVimProcessWithArguments:args workingDirectory:nil];
     }
 }
 
+/// Open a new Vim window, potentially taking from cached (if preload is used).
+///
+/// @param mode Determine whether to use clean mode or not. Preload will only
+/// be used if using normal mode.
+///
+/// @param activate Activate the window after it's opened.
+- (void)openNewWindow:(enum NewWindowMode)mode activate:(BOOL)activate
+{
+    return [self openNewWindow:mode activate:activate extraArgs:nil];
+}
+
 - (IBAction)newWindow:(id)sender
 {
     ASLogDebug(@"Open new window");