NES: minor tweaks of no consequence

BizHawk.Emulation.Cores/Consoles/Nintendo/NES/BoardSystem.cs

@@ -295,7 +295,8 @@ namespace BizHawk.Emulation.Cores.Nintendo.NES
 			protected void AssertVram(params int[] vram) { Assert_memtype(Cart.vram_size, "vram", vram); }
 			protected void Assert_memtype(int value, string name, int[] valid)
 			{
-				if (DisableConfigAsserts) return;
+				// only disable vram and wram asserts, as UNIF knows its prg and chr sizes
+				if (DisableConfigAsserts && (name == "wram" || name == "vram")) return;
 				foreach (int i in valid) if (value == i) return;
 				Assert(false, "unhandled {0} size of {1}", name,value);
 			}

BizHawk.Emulation.Cores/Consoles/Nintendo/NES/Boards/ExROM.cs

@@ -18,7 +18,8 @@ using BizHawk.Emulation.Common.Components;
 //FUTURE - we may need to split this into a separate MMC5 class. but for now it is just a pain.
 namespace BizHawk.Emulation.Cores.Nintendo.NES
 {
-	[NES.INESBoardImplPriority]
+	//MMC5 isn't actually all that common
+	//[NES.INESBoardImplPriority]
 	public sealed class ExROM : NES.NESBoardBase
 	{
 		//configuraton