Fix cell picker for images with negative spacing.

If the spacing of the image data was negative in any of the three
dimensions, it resulted in a failed bounding box test for the image
in the vtkCellPicker.  This patch adds a check for negative spacing.

Change-Id: Ia6b7c31fa78988900ce2e68f0ee8cd9bc8ecbf8d
Merge topic 'cell-picker-image-spacing' into master

8eb00d2f Fix cell picker for images with negative spacing.
Update system font test baseline.

Change-Id: I1a51d9f1c44ce55863077bd2dfba8deacc53f26b
Merge topic 'update-baseline' into master

67ee41e8 Update system font test baseline.
Fix uninitialized array warnings.

There were dashboard warnings about array elements that might be
used uninitialized.  Set the arrays to reasonable default values.

Change-Id: I6507d778ff315367c2798b1568e2b4eac7731cd2
vtkOStreamWrapper: Support std::string

This will allow std::string to be used with vtkSet/Get macros.

See discussion thread

 VTK coding conventions clarification
 http://www.vtk.org/pipermail/vtk-developers/2014-March/014867.html

Forward-declare std::basic_string<> to avoid including <string>
everywhere.  Use std::allocator<> and std::char_traits<> declarations
that we know vtkSystemIncludes.h brought in before including the
vtkOStreamWrapper.h header.

Inspired-by: David C. Lonie <david.lonie@kitware.com>
Change-Id: I8f4d5a032c4348b270c69bd2e33f64bf708108c5
Merge topic 'init-warnings' into master

f0825f48 Fix uninitialized array warnings.
Merge topic 'core-string' into master

7feab87c vtkOStreamWrapper: Support std::string