Fix #47 User can block a project on his client

src/com/sheepit/client/Error.java

@@ -38,6 +38,7 @@ public class Error {
 		RENDERER_CRASHED(12),
 		RENDERER_OUT_OF_VIDEO_MEMORY(13),
 		RENDERER_KILLED(14),
+		RENDERER_KILLED_BY_USER(20),
 		RENDERER_MISSING_LIBRARIES(15),
 		FAILED_TO_EXECUTE(16),
 		OS_NOT_SUPPORTED(17),
@@ -152,6 +153,8 @@ public class Error {
 				return "Failed to launch renderer. Please check if you have necessary libraries installed and if you have enough free space in your working directory.";
 			case RENDERER_KILLED:
 			    return "The renderer stopped because either you asked to stop or the server did (usually for a render time too high).";
+			case RENDERER_KILLED_BY_USER:
+				return "The renderer stopped because you've blocked its project.";
 			case SESSION_DISABLED:
 				return "The server has disabled your session. Your client may have generated a broken frame (GPU not compatible, not enough RAM/VRAM, etc).";
 			case RENDERER_NOT_AVAILABLE: