Update relocation data handling

When we have relocation data available, the code currently skips the
process of matching an address with a label for a PEA instruction when
the instruction in question doesn't have reloc data.  This does a
great job of separating code that pushes parts of addresses from code
that pushes constants.

This change expands the behavior to exclude instructions with 16-bit
address operands that use the Data Bank Register, e.g. "LDA abs"
and "LDA abs,X".  This is particularly useful for code that accesses
structured data using the operand as the structure offset, e.g.
"LDX addr" / "LDA $0000,X"

The 20212-reloc-data test has been updated to check the behavior.

SourceGen/RuntimeData/Help/advanced.html

@@ -303,6 +303,9 @@ it is with the <code>JMP $1000</code> at the start of the file.</p>
 
 <h2><a name="reloc-data">OMF Relocation Dictionaries</a></h2>
 
+<p><i>This feature is considered experimental.  Some features,
+like cross-reference tracking, may not work correctly with it.</i></p>
+
 <p>65816 code can be tricky to disassemble for a number of reasons.
 24-bit addresses are formed from 16-bit data-access operands by combining
 with the Data Bank Register, which often requires a bit of manual
@@ -347,9 +350,42 @@ even without setting the DBR.</p>
 02/318f: a9 03 00              lda     #L30000 >> 16
 02/3192: 8d 7a 3f              sta     L23F78 & $ffff +2
 </pre>
-<p>This feature is still considered "experimental".  There are some
-issues with it, e.g. the cross-reference table may show an incorrect
-offset.</p>
+<p>The absence of relocation data can be a useful signal as well.  For
+example, when pushing arguments for a toolbox call, the disassembler
+can tell the difference between addresses and constants without needing
+emulation or pattern-matching, because only the addresses get
+relocated.  Consider this bit of source code:</p>
+<pre>
+           lda   &lt;total_records
+           pha
+           pea   linebuf|-16
+           pea   linebuf+65
+           pea   $0005
+           pea   $0000
+           _Int2Dec
+</pre>
+<p>Without relocation data, it becomes:</p>
+<pre>
+02/0aa8: a5 42                 lda     $42
+02/0aaa: 48                    pha
+02/0aab: f4 02 00              pea     L20002 & $ffff
+02/0aae: f4 03 31              pea     L23103 & $ffff
+02/0ab1: f4 05 00              pea     L20005 & $ffff
+02/0ab4: f4 00 00              pea     L20000 & $ffff
+02/0ab7: a2 0b 26              ldx     #Int2Dec
+02/0aba: 22 00 00 e1           jsl     Toolbox
+</pre>
+<p>If we treat the non-relocated operands as constants:</p>
+<pre>
+02/0aa8: a5 42                 lda     $42
+02/0aaa: 48                    pha
+02/0aab: f4 02 00              pea     L230C2 >> 16
+02/0aae: f4 03 31              pea     L23103 & $ffff
+02/0ab1: f4 05 00              pea     $0005
+02/0ab4: f4 00 00              pea     $0000
+02/0ab7: a2 0b 26              ldx     #Int2Dec
+02/0aba: 22 00 00 e1           jsl     Toolbox
+</pre>
 
 
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