mapper cleanups (#494)

* m215: Fix support for submapper 1 cart

* Switch UNL43272 to new Mapper242 implementation

* Merge mappers BMC-70in1/B and 236

* Merge 58/213/GK-192

* Assign GS-2004/GS-2014 to mapper 283

* Cleanup

Co-authored-by: negativeExponent <negativeExponent@users.noreply.github.com>

src/boards/236.c

@@ -33,13 +33,16 @@ static SFORMAT StateRegs[] =
 static void Sync(void)
 {
 	int prg;
+	int chr;
 	if (chrramvariant)
 	{
 		prg = reg[1] &7 | reg[0] <<3;
+		chr = 0;
 	}
 	else
 	{
-		prg = reg[1] &15;
+		prg = reg[1] & 0x0F;
+		chr = reg[0] & 0x0F;
 	}
 	switch (reg[1] >>4 &3)
 	{
@@ -56,11 +59,10 @@ static void Sync(void)
 			setprg16(0xC000, prg);
 			break;
 	}
-	setchr8(reg[0] &15);
+	setchr8(chr);
 	setmirror((reg[0] >>5 &1) ^1);
 }
 
-
 static DECLFR(M236Read)
 {
 	if ((reg[1] >>4 &3) ==1)