Multiple fixes to allow PDFio to read more edge-case PDFs.

- Update _pdfioFileGets to allow for really long lines where it
  doesn't matter if we lose the end of the line.
- Update "startxref" detection at the end of the file.
- Refactor repair logic so that you just get a single WARNING about
  the repair (debug messages available for testing)
- Allow whitespace after the "obj" in the object header.
- Make sure to close xref stream on error.
- Update predictor code to support Colors <= 32 (some implementations
  set Colors to the number of bytes per record in the xref stream,
  which prevents the predictor from doing anything...)
- Allow CR CR in xref table.
- Clear old trailer/root/pages/etc. objects when repairing, update
  existing objects that were already found in load_xref.
- Don't set current object in pdfioObjectCreate/OpenStream if the
  stream can't be created/opened.

pdfio-stream.c

@@ -259,7 +259,7 @@ _pdfioStreamCreate(
     {
       colors = 1;
     }
-    else if (colors < 0 || colors > 4)
+    else if (colors < 0 || colors > 32)
     {
       _pdfioFileError(st->pdf, "Unsupported Colors value %d.", colors);
       free(st);
@@ -532,7 +532,7 @@ _pdfioStreamOpen(pdfio_obj_t *obj,	// I - Object
       {
         colors = 1;
       }
-      else if (colors < 0 || colors > 4)
+      else if (colors < 0 || colors > 32)
       {
         _pdfioFileError(st->pdf, "Unsupported Colors value %d.", colors);
 	goto error;