add script to fix the navigation links when the index order changes

re-linking the pages manually makes one's head explode, so automate it.

doc/fixnavi.pl

+#! /usr/bin/perl -w
+
+use strict;
+
+my $file = $ARGV[0];
+open FILE, $file or die "File $file cannot be opened.";
+my @toc = ();
+my %title2page = ();
+my $doctitle = "";
+my $curpage = "";
+my $intoc = 0;
+while (<FILE>) {
+    if (!$intoc) {
+        if (keys(%title2page) == 1 && /^\h*\\list/) {
+            $intoc = 1;
+        } elsif (/^\h*\\page\h+(\H+)/) {
+            $curpage = $1;
+        } elsif (/^\h*\\title\h+(.+)$/) {
+            if ($curpage eq "") {
+                die "Title '$1' appears in no \\page\n";
+            }
+            $title2page{$1} = $curpage;
+            $doctitle = $1 if (!$doctitle);
+            $curpage = "";
+        }
+    } else {
+        if (/^\h*\\endlist/) {
+            $intoc = 0;
+        } elsif (/^\h*\\o\h+\\l{(.*)}$/) {
+            push @toc, $1;
+        }
+    }
+}
+close FILE;
+
+my %prev = ();
+my %next = ();
+my $last = $doctitle;
+for my $title (@toc) {
+    $next{$last} = $title2page{$title};
+    $prev{$title} = $title2page{$last};
+    $last = $title;
+}
+
+open IN, $file or die "File $file cannot be opened a second time?!";
+open OUT, '>'.$file.".out" or die "File $file.out cannot be created.";
+my $cutting = 0;
+while (<IN>) {
+    if (!$cutting) {
+        if (/^\h*\\contentspage/) {
+            $cutting = 1;
+        }
+    } else {
+        if (/^\h*\\title\h+(.+)$/) {
+            print OUT "    \\previouspage ".$prev{$1} if ($prev{$1});
+            print OUT "    \\page ".$title2page{$1};
+            print OUT "    \\nextpage ".$next{$1} if ($next{$1});
+            print OUT "\n";
+            $cutting = 0;
+        } else {
+            next;
+        }
+    }
+    print OUT $_;
+}
+close OUT;
+close IN;
+
+rename($file.".out", $file) or die "Cannot replace $file with new version.";

doc/qtcreator.qdoc

+// **********************************************************************
+// NOTE: the sections are not ordered by their logical order to avoid
+// reshuffling the file each time the index order changes (i.e., often).
+// Run the fixnavi.pl script to adjust the links to the index order.
+// **********************************************************************
+
 /*!
     \contentspage{index.html}{Qt Creator}
     \page index.html