6719 - error-checking for 'index' instructions

1000+ LoC spent; just 300+ excluding tests.

Still one known gap; we don't check the entirety of an array's element
type if it's a compound. So far we just check if say both sides start with
'addr'. Obviously that's not good enough.

apps/factorial.mu

@@ -31,8 +31,8 @@ fn test-factorial {
   check-ints-equal result 0x78 "F - test-factorial"
 }
 
-fn main args-on-stack: (addr array (addr array byte)) -> exit-status/ebx: int {
-  var args/eax: (addr array (addr array byte)) <- copy args-on-stack
+fn main args-on-stack: (addr array addr array byte) -> exit-status/ebx: int {
+  var args/eax: (addr array addr array byte) <- copy args-on-stack
   var tmp/ecx: int <- length args
   $main-body: {
     # if (len(args) <= 1) factorial(5)

apps/subx-params.subx

@@ -12,7 +12,7 @@ Input-size:
 
 # number of labels we can translate to addresses
 Max-labels:
-  0x30000/imm32/24K-labels/192KB
+  0x60000/imm32/24K-labels/192KB
 
 # capacity of trace-stream
 Trace-size: