make sure BASIC rom is banked in again when program exits

compiler/res/prog8lib/cx16/syslib.p8

@@ -517,8 +517,6 @@ asmsub  init_system()  {
         jsr  c64.CHROUT
         lda  #147       ; clear screen
         jsr  c64.CHROUT
-        ldx  #4
-        stx  $01        ; select rom bank 4 (enable basic again)
         lda  #0
         tax
         tay

compiler/src/prog8/compiler/target/cpu6502/codegen/AsmGen.kt

@@ -157,7 +157,12 @@ internal class AsmGen(private val program: Program,
                 pha""")
         }
 
-        jmp("main.start")
+        // make sure that on the cx16 and c64, basic rom is banked in again when we exit the program
+        when(compTarget.name) {
+            Cx16Target.name -> out("  jsr  main.start |  lda  #4 |  sta  $01 |  rts")
+            C64Target.name -> out("  jsr  main.start |  lda  #31 |  sta  $01 |  rts")
+            else -> jmp("main.start")
+        }
     }
 
     private fun slaballocations() {

examples/test.p8

@@ -1,22 +1,15 @@
 %import textio
 %import floats
-%zeropage dontuse
+%zeropage basicsafe
 
 main {
 
     sub start() {
+        ;cx16.rombank(4)
         float f1 = 9.9999
         float f2 = 8.8888
         float f3 = 0.1111
 
-        %asm {{
-            phx
-            ldy  #<f1
-            lda  #>f1
-            jsr  $FE42
-            jsr  $FE7B
-            plx
-        }}
         f3=cos(f3)
 
         floats.print_f(f1)
@@ -28,9 +21,10 @@ main {
         f3 = cos(f3)
         floats.print_f(f3)
 
+        cx16.rombank(0)
+
         txt.print("ok!\n")
 
         sys.wait(2*60)
-
     }
 }