Changed c128 accelerator code and documention to include both C64 and C128 support.

libsrc/c128/acc_detect_c128.s

@@ -0,0 +1,24 @@
+;
+; Marco van den Heuvel, 2018-04-23
+;
+
+; unsigned char detect_c128 (void);
+;
+;/* Check if the C128 8502 CPU is the current CPU.
+; *
+; * Possible return values:
+; * 0x00  : C128 8502 is not the current CPU
+; * 0x01  : C128 8502 is the current CPU
+; */
+
+        .export         _detect_c128
+
+        .include        "accelerator.inc"
+
+_detect_c128:
+        ldx     #$00
+        lda     #$01
+
+; Make sure the CPU is a 8502
+        .byte   $3A                   ; NOP on 8502, DEA on 65(S)C(E)02, 4510 and 65816
+        rts