Nektar: Fix command order in CMakeLists.txt

In Plugins/Nektar/CMakeLists.txt, call cmake_minimum_required() before
project().  Drop the unnecessary calls to both commands in the
ParaViewPlugin subdirectory.

Change-Id: Ie3294961754a7274523c42a90ee246b1f01307a5
Drop use of the CMake LOCATION target property

CMake 3.0 introduced policy CMP0026 to disallow use of the LOCATION
target property.  Drop our unused lookup of the protoc_compiler
LOCATION.  Replace our lookup of the kwProcessXML LOCATION with a direct
reference to the target in the custom command.  CMake will replace
the reference with the location while generating the project.

Change-Id: I78ffa82eb2aa57b30586e3f79102d2dfdaa07666
Drop outdated CMake Policy settings

Drop explicit calls to cmake_policy() to set policies that are already
set by our cmake_minimum_required(VERSION) calls.  Drop our setting of
CMP0017 to OLD because.  It was incorrectly set to OLD to silence a
warning but should have been set to NEW to silence the warning, and that
is now done by our cmake_minimum_required call.

Change-Id: I6cc32dd987510f34defc0d0b03e1925ce557ff4a
Set MACOSX_RPATH property default consistently across CMake versions

The MACOSX_RPATH target property was introduced in CMake 2.8.12, but we
currently allow CMake 2.8.8.  Set CMAKE_MACOSX_RPATH to 0 by default
so that we get consistent behavior across all versions of CMake.
Leave a comment explaining when the default should be updated.

Change-Id: I3edab4a1fe67456dce4f078a8fa40ac725b449cf
Merge topic 'cleanup-cmake'

919d5ec6 Set MACOSX_RPATH property default consistently across CMake versions
7747ee9a Drop outdated CMake Policy settings
13cccad8 Drop use of the CMake LOCATION target property
6de39871 Nektar: Fix command order in CMakeLists.txt