Try to preserve most of the manual changes done to libtiff sources in
wxWidgets, dropping just some VC6-specific workarounds which are not
needed any more.
The conversion is very superficial and there are probably many problems in the
Markdown rendering, but this is the first step towards making these documents
more readable when viewing them online.
git-svn-id: https://svn.wxwidgets.org/svn/wx/wxWidgets/trunk@76690 c3d73ce0-8a6f-49c7-b76d-6d57e0e08775