Make vtkDataArray::ComputeRange() thread-safe

This changes the vtkDataArray::ComputeRange() method to be thread-
safe by passing it the range array rather than having it set the
internal 'this->Range' variable.

This also updates GetRange() to use the thread-safe API.

Change-Id: Ieb281e26f8f0b6a1f521176294d388e026ad0865
Fixed a few OS X-related comments.

This document needs a lot more updating...

Change-Id: I71753427a77c8c43fb0030327dff46cdb706ed58
Repare vtkCutter for all data object types.

vtkCutter was no longer able to handle all kind of inputs because of
a faulty else if.

Change-Id: I31768e0df1fd1edf0e54ef55d3a066ad41c86684
Merge topic 'thread-safe-compute-range' into master

51f66a47 Make vtkDataArray::ComputeRange() thread-safe
Merge topic 'readme-updates' into master

c63c8aaf Fixed a few OS X-related comments.
Accumulate character data between calls to CharacterDataHandler.

This fixes a bug where character data was split across two 4k
buffer payloads (read by vtkXMLParser) leading to incorrect parsing
of the text (the first bit was discarded and the second bit was treated
as the entire string).

Change-Id: I1196a8d4bc7a55aaf5a5c5113e9c4112f97858de
Merge topic 'bodr-parser-bug' into master

47dba442 Accumulate character data between calls to CharacterDataHandler.
Fixed the 'double' variant of SetColor to use 1.0 not 255

I believe there was a copy-paste here.  The alpha was being
set to 255 (notably not written 255.0) instead of 1.0 for
the 'double' case, where rgba values should (I believe)
range from 0.0 to 1.0.  Fixes undefined behaviour reported
by clang:

runtime error: value 65025 is outside the range of representable values of type 'unsigned char'

that happens when this 255 value was itself later multiplied
by 255 in an attempt to change it to uint8 range.

Change-Id: I85c718bcbc275a328bb6264222d4dec2c3110781
Merge topic 'vtkCutter-all-dataObjectType' into master

7c6da061 Repare vtkCutter for all data object types.
Merge topic 'sanitize-float-cast-overflow' into master

061dc2bc Fixed the 'double' variant of SetColor to use 1.0 not 255