Fix errors in manual

SourceGen/RuntimeData/Help/advanced.html

@@ -22,7 +22,7 @@ popular systems, but you can create your own.  This can be handy if a
 few different projects are coded against a common library.</p>
 
 <p>If two symbols have the same value, the older symbol is replaced by
-the newer one.  This is why the order in which symbols file are loaded
+the newer one.  This is why the order in which symbol files are loaded
 matters.</p>
 
 <p>Platform symbol files consist of comments, commands, and symbols.

SourceGen/RuntimeData/Help/codegen.html

@@ -169,9 +169,9 @@ code, but also needs to know how to handle the corner cases.</p>
   <li>If you set the <code>--case-sensitive</code> flag, <b>all</b> opcodes
     and operands must be lower-case.  Most of the SourceGen options that
     cause things to appear in upper case must be disabled.</li>
-  <li>For 65816, selecting the bank byte is done with the back-quote ('`')
-    rather than the caret ('^').  (There's a note in the docs to the effect
-    that they plan to move to carets.)</li>
+  <li>For 65816, selecting the bank byte is done with the grave accent
+    character ('`') rather than the caret ('^').  (There's a note in the
+    docs to the effect that they plan to move to carets.)</li>
   <li>The arguments to COP and BRK require immediate-mode syntax
     (<code>COP #$03</code> rather than <code>COP $03</code>).
   <li>For historical reasons, the default behavior of the assembler is to

SourceGen/RuntimeData/Help/mainwin.html

@@ -364,7 +364,7 @@ from the
 <a href="settings.html#project-properties">project properties</a> editor,
 or simply by hitting Ctrl+D.  Hit that, apply the hint, then hit it
 again to re-enable the string &amp; fill analyzer.</p>
-<p>Another approach is to can use the "Toggle Single-Byte Format"
+<p>Another approach is to use the "Toggle Single-Byte Format"
 menu item to "flatten" the item.</p>