Integrate MSW, OS X and iOS build instructions into doxygen

Make build instructions available in doxygen but keep the old
folder structure.

docs/msw/gtk.md

@@ -0,0 +1,82 @@
+Building wxGTK port with Win32 GDK backend {#plat_msw_gtk}
+------------------------------------------
+
+GTK+ widget toolkit has multiple GDK backends and one of them is Win32.
+It is a wrapper around Windows API.
+
+See http://www.gtk.org/download/win32.php
+
+These notes don't consider building wxGTK with X11 backend under Windows.
+
+Building steps:
+
+1. wxGTK/Win32 build is similar to wxMSW one and you should have configured
+and be able to build wxWidgets as described in @ref plat_msw_install
+
+2. wxGTK/Win32 is disabled by default in wxWidgets, you need to enable it
+in bakefiles manually. Apply following patch manually or using Cygwin:
+
+        patch -p0 < docs/msw/gtkfix.patch
+
+Regenerate required make/project files:
+
+    cd build\bakefiles
+    bakefile_gen
+
+3. Download GTK+ for Windows and uncompress files in the directory
+without spaces in the name. We suppose later that GTK+/Win32 is
+in the C:\gtk directory.
+
+    http://ftp.gnome.org/pub/gnome/binaries/win32/gtk+/2.24/gtk+_2.24.10-1_win32.zip
+
+4. Building
+
+4.1 If you are using Visual C++ project files you need to setup GTK+ 2 include directories
+
+    C:\gtk\lib\include\gtk-2.0
+    C:\gtk\lib\include\glib-2.0
+    C:\gtk\lib\include\cairo
+    C:\gtk\lib\include\pango-1.0
+    C:\gtk\lib\include\gdk-pixbuf-2.0
+    C:\gtk\lib\include\atk-1.0
+    C:\gtk\lib\glib-2.0\include
+    C:\gtk\lib\gtk-2.0\include
+
+and library directory
+
+    C:\gtk\lib\
+
+See http://msdn.microsoft.com/en-us/library/t9az1d21(v=vs.90).aspx
+
+Open solution file in build\msw directory, select "GTK+ Debug" solution
+configuration and build the solution. To be sure that everything is as expected
+you can build minimal sample.
+
+GTK+ is linked to wxWidgets always as DLL, so C:\gtk\bin directory should be
+in %PATH% environment variable before application run.
+
+4.2 You can also build using nmake:
+
+    set INCLUDE=C:\gtk\lib\glib-2.0\include\;C:\gtk\lib\gtk-2.0\include\;C:\gtk\include\cairo\;C:\gtk\include\pango-1.0\;C:\gtk\include\gtk-2.0\;C:\gtk\include\glib-2.0\;C:\gtk\include\gdk-pixbuf-2.0\;C:\gtk\include\atk-1.0\;
+    set LIB=C:\gtk\lib\;
+    set PATH=C:\gtk\bin\;%PATH%;
+
+    nmake -f makefile.vc "TOOLKIT=GTK" "TOOLKIT_VERSION=2"
+
+or with MinGW:
+
+    set CXXFLAGS=%CXXFLAGS% -IC:\gtk\include\gtk-2.0
+    set CXXFLAGS=%CXXFLAGS% -IC:\gtk\include\glib-2.0
+    set CXXFLAGS=%CXXFLAGS% -IC:\gtk\include\cairo
+    set CXXFLAGS=%CXXFLAGS% -IC:\gtk\include\pango-1.0
+    set CXXFLAGS=%CXXFLAGS% -IC:\gtk\include\gdk-pixbuf-2.0
+    set CXXFLAGS=%CXXFLAGS% -IC:\gtk\include\atk-1.0
+    set CXXFLAGS=%CXXFLAGS% -IC:\gtk\lib\glib-2.0\include
+    set CXXFLAGS=%CXXFLAGS% -IC:\gtk\lib\gtk-2.0\include
+    set CFLAGS=%CXXFLAGS%
+    set LDFLAGS=%LDFLAGS% -LC:\gtk\lib
+    set PATH=C:\gtk\bin\;%PATH%;
+
+    mingw32-make -f makefile.gcc "TOOLKIT=GTK" "TOOLKIT_VERSION=2"
+
+5. Now you can use wxGTK/Win32 as wxMSW in your applications.