FindITK: Drop this ancient compatibility module

The FindITK module only existed to help find_package(ITK) calls work in
old projects written to use "USE_ITK_FILE" instead of "ITK_USE_FILE".
Drop it to allow find_package(ITK) calls to search for ITKConfig.cmake
directly.

Help/module/FindITK.rst

@@ -1 +1,10 @@
-.. cmake-module:: ../../Modules/FindITK.cmake
+FindITK
+-------
+
+This module no longer exists.
+
+This module existed in versions of CMake prior to 3.1, but became
+only a thin wrapper around ``find_package(ITK NO_MODULE)`` to
+provide compatibility for projects using long-outdated conventions.
+Now ``find_package(ITK)`` will search for ``ITKConfig.cmake``
+directly.

Modules/FindITK.cmake

@@ -1,61 +0,0 @@
-#.rst:
-# FindITK
-# -------
-#
-# Find an ITK installation or build tree.
-
-# When ITK is found, the ITKConfig.cmake file is sourced to setup the
-# location and configuration of ITK.  Please read this file, or
-# ITKConfig.cmake.in from the ITK source tree for the full list of
-# definitions.  Of particular interest is ITK_USE_FILE, a CMake source file
-# that can be included to set the include directories, library directories,
-# and preprocessor macros.  In addition to the variables read from
-# ITKConfig.cmake, this find module also defines
-#  ITK_DIR  - The directory containing ITKConfig.cmake.
-#             This is either the root of the build tree,
-#             or the lib/InsightToolkit directory.
-#             This is the only cache entry.
-#
-#  ITK_FOUND - Whether ITK was found.  If this is true,
-#              ITK_DIR is okay.
-#
-#  USE_ITK_FILE - The full path to the UseITK.cmake file.
-#                 This is provided for backward
-#                 compatibility.  Use ITK_USE_FILE
-#                 instead.
-
-#=============================================================================
-# Copyright 2001-2010 Kitware, Inc.
-#
-# Distributed under the OSI-approved BSD License (the "License");
-# see accompanying file Copyright.txt for details.
-#
-# This software is distributed WITHOUT ANY WARRANTY; without even the
-# implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.
-# See the License for more information.
-#=============================================================================
-# (To distribute this file outside of CMake, substitute the full
-#  License text for the above reference.)
-
-# Use the Config mode of the find_package() command to find ITKConfig.
-# If this succeeds (possibly because ITK_DIR is already set), the
-# command will have already loaded ITKConfig.cmake and set ITK_FOUND.
-if(NOT ITK_FOUND)
-  set(_ITK_REQUIRED "")
-  if(ITK_FIND_REQUIRED)
-    set(_ITK_REQUIRED REQUIRED)
-  endif()
-  set(_ITK_QUIET "")
-  if(ITK_FIND_QUIETLY)
-    set(_ITK_QUIET QUIET)
-  endif()
-  find_package(ITK ${_ITK_REQUIRED} ${_ITK_QUIET} NO_MODULE
-    NAMES ITK InsightToolkit
-    CONFIGS ITKConfig.cmake
-    )
-endif()
-
-if(ITK_FOUND)
-  # Set USE_ITK_FILE for backward-compatibility.
-  set(USE_ITK_FILE ${ITK_USE_FILE})
-endif()