macOS Sierra and above Blocked Plugin Fix + Legacy Xcode Building

Thanks to @xrubioj for pointing the his solution

This fix addresses the Blocked Plugin issue and UI properties are
usable than a blanked out UI from @xrubioj original PR
radiant-player#670

Legacy Build System is needed so i enabled it in my workspace

Only if you set `UseModernBuildSystem=NO` in the Workspace setting

```
Xcode 9.3 adds a new IDEWorkspaceChecks.plist file to a workspace’s
shared data, to store the state of necessary workspace checks.
Committing this file to source control will prevent unnecessary
rerunning of those checks for each user opening the workspace.
```

radiant-player-mac.xcworkspace/xcshareddata/IDEWorkspaceChecks.plist

@@ -0,0 +1,8 @@
+<?xml version="1.0" encoding="UTF-8"?>
+<!DOCTYPE plist PUBLIC "-//Apple//DTD PLIST 1.0//EN" "http://www.apple.com/DTDs/PropertyList-1.0.dtd">
+<plist version="1.0">
+<dict>
+	<key>IDEDidComputeMac32BitWarning</key>
+	<true/>
+</dict>
+</plist>

radiant-player-mac.xcworkspace/xcshareddata/WorkspaceSettings.xcsettings

@@ -2,6 +2,8 @@
 <!DOCTYPE plist PUBLIC "-//Apple//DTD PLIST 1.0//EN" "http://www.apple.com/DTDs/PropertyList-1.0.dtd">
 <plist version="1.0">
 <dict>
+	<key>BuildSystemType</key>
+	<string>Original</string>
 	<key>IDEWorkspaceSharedSettings_AutocreateContextsIfNeeded</key>
 	<false/>
 </dict>

radiant-player-mac/WebView/CustomWebView.m

@@ -30,6 +30,22 @@ - (void)awakeFromNib
     [self setAcceptsTouchEvents:YES];
     [self addSubview:swipeView];
 
+    // Check if we are macOS Sierra or higher
+    if (floor(NSAppKitVersionNumber) >= NSAppKitVersionNumber10_12) {
+
+        // Since we are doing a customer user-agent, lets show the app version of Radiant
+        NSString * RadiantVersion = [[NSBundle mainBundle] objectForInfoDictionaryKey: @"CFBundleShortVersionString"];
+
+        // Push and set our custom strings
+        NSString* RadiantBarakaAgent = [NSString stringWithFormat: @"Safari Radiant Player/%@", RadiantVersion];
+
+        //Use our default user-agent and push our custom string
+        [self setApplicationNameForUserAgent:RadiantBarakaAgent];
+
+        //Testing is needed right?
+        //NSLog(@"navigator.userAgent = %@", RadiantBarakaAgent);
+    }
+
     [self setResourceLoadDelegate:self];
     [self setUIDelegate:self];
     [self setFrameLoadDelegate:self];
@@ -321,4 +337,4 @@ - (NSPoint)touchPositionForTouches:(NSSet *)touches
     return position;
 }
 
-@end
+@end