* First set of patches for making mergable CHM files, committed after a point with 0 regressions.
    * IDXHDR internal file added.
    * better defaults for [Windows] lines.
    * Avoid duplication topic if both in index and separately in hhp. Size reduction for many hhp scenarios, no difference for fpdoc
    * System section 13 (copy of idxhdr)
    * index/toc files registered as topic type 2. (incontents field)
      * duplicate code for creating topics cleaned up, all now use addtopic
    * correct number of topics in system file.
    * some bugfixes in binary index.
    * some more global properties supported in sitemaps.

 * many extra (dumping) options for chmls tool.

git-svn-id: http://svn.freepascal.org/svn/fpc/trunk@24979 3ad0048d-3df7-0310-abae-a5850022a9f2