Fix up TODO for ABI changes

TODO

@@ -1,36 +1,47 @@
 Next ABI
 ========
 
-Do these things next time we have to break binary compatibility
-
- * Check all classes that don't use the Members pattern and see if
-   they should be converted. Most of the pipeline classes should be
-   converted.
-
- * Pl_Buffer's internal structure is not right for what it does. It
-   was modified for greater efficiency, but it was done in a way that
-   preserved binary compatibility, so the implementation is a bit
-   convoluted.
-
  * Rename QUtil::strcasecmp since strcasecmp is a macro on some
    platforms. See #242.
 
- * Check all overloaded methods to see if any can be eliminated by
-   using defaulted arguments. See ../misc/find-overloaded-functions.pl
-   (not in source repo)
-
  * Get rid of the version of QPDF::copyForeignObject with the bool
    unused parameter.
 
  * Remove version of QPDFTokenizer::expectInlineImage with no
    arguments.
 
- * Consider whether to build with -fvisibility=hidden by default. See
-   #302 for discussion.
+ * Build with -fvisibility=hidden by default. Fix QPDF_DLL. See #302
+   for discussion. See also https://gcc.gnu.org/wiki/Visibility
 
- * See if there is a way to provide an option to use higher
-   compression with zlib. See #113. This can be done by adding options
-   to Pl_Flate and having QPDFWriter optionally use those options.
+ * Check all classes that don't use the Members pattern and see if
+   they should be converted. Most of the pipeline classes should be
+   converted.
+
+   Buffer.hh
+   BufferInputSource.hh
+   FileInputSource.hh
+   InputSource.hh
+   Pl_Buffer.hh
+   Pl_Concatenate.hh
+   Pl_Count.hh
+   Pl_DCT.hh
+   Pl_Discard.hh
+   Pl_Flate.hh
+   Pl_RunLength.hh
+   Pl_StdioFile.hh
+   QPDFExc.hh
+   QPDFObjGen.hh
+   QPDFSystemError.hh
+   QPDFXRefEntry.hh
+
+ * Pl_Buffer's internal structure is not right for what it does. It
+   was modified for greater efficiency, but it was done in a way that
+   preserved binary compatibility, so the implementation is a bit
+   convoluted.
+
+ * Check all overloaded methods to see if any can be eliminated by
+   using defaulted arguments. See ../misc/find-overloaded-functions.pl
+   (not in source repo)
 
 Lexical
 =======
@@ -120,6 +131,11 @@ directory or that are otherwise not publicly accessible. This includes
 things sent to me by email that are specifically not public. Even so,
 I find it useful to make reference to them in this list
 
+ * See if there is a way to provide an option to use higher
+   compression with zlib. See #113. This can be done by adding options
+   to Pl_Flate and having QPDFWriter optionally use those options.
+   Also increasing the buffer size may help.
+
  * Add support for writing name and number trees
 
  * Figure out how to render Gajić correctly in the PDF version of the