Fix gcc -Wliteral-suffix warning

Add extra whitespace in png.h to fix gcc warning:

VTK/ThirdParty/png/vtkpng/png.h:2217:29: warning: invalid suffix on literal; C++11 requires a space between literal and identifier [-Wliteral-suffix]
      fprintf(PNG_DEBUG_FILE,"%s"m,(num_tabs==1 ? "\t" : \
                             ^

I have not checked or synced with upstream
partly because there isn't even a readme
that tells me what version of libpng this is
or what custom changes have been made, if any.

Change-Id: I7ea3b0787e9c62964ca297ad73dcc15afaa00852
Merge topic 'png-warnings' into master

0482ec09 Fix gcc -Wliteral-suffix warning
Integrated an object-oriented, phased testing approach for web tests.

Added and refactored some base classes written by Roni Choudhury
to the vtk.web.testing module.  These classes introduce a phased
testing approach where subclasses have an opportunity to override
the 5 phases of testing: 1) initialization, 2) setup, 3) capture,
4) postprocess, and 5) cleanup.

Now the test scripts are written as subclasses of one of the three
new testing base classes and override some or all of the testing
phases.  The scripts are dynamically loaded as modules, and then
inspection is used to find the class to instantiate at run time.

The integration of these test classes also provides the ability
to use vtk.vtkTesting to achieve support for multiple baseline
images.  An additional benefit of the testing classes is easy
support for multiple browsers.

Change-Id: I4de223e9b7fce4ba1b59ba21ed46c6bbc1e9d5c5
Merge topic 'pvweb-integrate-test-packages-alternate' into master

16145dfc Integrated an object-oriented, phased testing approach for web tests.
Fixed/suppressed various dashboard compiler warnings

Change-Id: Ie966625bee8ca7fde4617d05f6dfcf85078c0696
Merge topic 'various-dashboard-warnings' into master

5b1f54f7 Fixed/suppressed various dashboard compiler warnings
Correct comment about required string encoding

Recently, VTK became more Unicode aware, and
vktTextActor supposedly now requires UTF-8.

Change-Id: I8e86c13a17d500844e71e924a2d4e2da97559508
Merge topic 'utf-comment' into master

41b56d9c Correct comment about required string encoding