Add documentation for the --graphviz support

This patch adds Modules/CMakeGraphVizOptions.cmake, which is used
only for generating documentation for the --graphviz support.

Alex
graphvizoptions: add copyright notice

Alex
OS X: If necessary, use xcrun to help find otool used to query install names.

This fixes querying for @rpath install names when using Xcode without
the command line tools installed.
add macros cmake_print_properties() and cmake_print_variables()

This patch adds the file CMakePrintHelpers.cmake, which provides
the macros (functions) cmake_print_properties() and cmake_print_variables(),
which are useful e.g. for debugging and make inspecting target (or other)
properties easier.

Alex
Revert "CTest: fix pre and post test commands with spaces" (#13887)

This reverts commit 6187876dea89618044e200808bcae75a18bd4043.

It was actually possible before to have paths with spaces in them, the spaces
just need to be quoted. This way spaces will work as argument separators.
FindPNG: improve library detection (#14301)

-add support for upcoming version 1.7
-improve version selection, use the major and minor of the requested version
 to generate the library suffix list
-support detection of release and debug libraries
Fix crash on export of target with empty INTERFACE_INCLUDE_DIRECTORIES.

The new feature of install(TARGETS ... INCLUDES DESTINATION) introduced
in commit 650e61f8 (Add a convenient way to add the includes install
dir to the INTERFACE., 2013-01-05) introduced this crash. If the
new feature is used with a target which has no
INTERFACE_INCLUDE_DIRECTORIES, a segfault occurred.
Merge topic 'DocumentGraphvisOptions'

692ecf4 graphvizoptions: add copyright notice
ee32673 Add documentation for the --graphviz support
Merge topic 'rpath-on-mac'

84698ab OS X: If necessary, use xcrun to help find otool used to query install names.
Merge topic 'FindPNG-dbg-rel'

2a79753 FindPNG: improve library detection (#14301)
Merge topic 'memcheck_pre_post_args'

c0756b6 Revert "CTest: fix pre and post test commands with spaces" (#13887)
Merge topic 'PrintHelperFunctions'

e32ff96 add macros cmake_print_properties() and cmake_print_variables()
Merge topic 'fix-export-includes-crash'

f868e47 Fix crash on export of target with empty INTERFACE_INCLUDE_DIRECTORIES.