Default to source bank in Format Address Table

When formatting a table of 16-bit addresses in 65816 code, the bank
byte was always being set to zero.  However, for "JMP (addr,X)", the
program bank is used.  We now default to that behavior.

The choice can be overridden as before (select 24-bit addresses with a
constant value for the bank byte).

SourceGen/WpfGui/FormatAddressTable.xaml.cs

@@ -419,7 +419,17 @@ namespace SourceGen.WpfGui {
                 }
             } else {
                 bankOff = -1;       // use constant
-                bankConst = 0;      // always bank 0
+
+                // Set the constant bank value equal to whichever bank the table lives in.
+                // This is correct for "JMP (addr,X)".  We use the offset of the first item
+                // in the range set, which is a little awkward to get to.
+                int offset = 0;
+                foreach (TypedRangeSet.Tuple tup in mSelection) {
+                    offset = tup.Value;
+                    break;
+                }
+                int addr = mProject.AddrMap.OffsetToAddress(offset);
+                bankConst = (byte)(addr >> 16);
             }
 
             if (IsSplitTable) {