Tutorial: Remove 'Consumer' example

This example was incomplete and did not follow the format of the tutorial.

Help/guide/tutorial/Consumer/CMakeLists.txt

-cmake_minimum_required(VERSION 3.10)
-
-if(NOT DEFINED CMAKE_CXX_STANDARD)
-  set(CMAKE_CXX_STANDARD 11)
-  set(CMAKE_CXX_STANDARD_REQUIRED True)
-endif()
-
-
-function(find_external_dependency name)
-  set(${name}_ROOT ""  CACHE PATH "Root directory to find ${name}")
-  mark_as_advanced(${name}_DIR)
-  find_package(${name} PATHS ${${name}_ROOT} REQUIRED)
-endfunction()
-
-
-project(Consumer)
-
-find_external_dependency(MathFunctions)
-
-add_library(consumer consumer.cxx)
-target_link_libraries(consumer PUBLIC MathFunctions)
-
-# install the consumer library
-install(TARGETS consumer DESTINATION bin EXPORT ConsumerTargets)
-
-# install the configuration targets
-install(EXPORT ConsumerTargets
-  FILE ConsumerTargets.cmake
-  DESTINATION lib/cmake/Consumer
-)
-
-include(CMakePackageConfigHelpers)
-# generate the config file that is includes the exports
-configure_package_config_file(${CMAKE_CURRENT_SOURCE_DIR}/Config.cmake.in
-  "${CMAKE_CURRENT_BINARY_DIR}/ConsumerConfig.cmake"
-  INSTALL_DESTINATION "lib/cmake/example"
-  NO_SET_AND_CHECK_MACRO
-  NO_CHECK_REQUIRED_COMPONENTS_MACRO
-  )
-
-# install the configuration file
-install(FILES
-  ${CMAKE_CURRENT_BINARY_DIR}/ConsumerConfig.cmake
-  DESTINATION lib/cmake/Consumer
-  )
-
-# generate the export targets for the build tree
-# needs to be after the install(TARGETS ) command
-export(EXPORT ConsumerTargets
-  FILE "${CMAKE_CURRENT_BINARY_DIR}/ConsumerTargets.cmake"
-)

Help/guide/tutorial/Consumer/Config.cmake.in

-
-@PACKAGE_INIT@
-
-include(CMakeFindDependencyMacro)
-
-function(find_external_dependency name)
-  set(${name}_ROOT ""  CACHE PATH "Root directory to find ${name}")
-  mark_as_advanced(${name}_DIR)
-  find_dependency(${name} PATHS ${${name}_ROOT} REQUIRED)
-endfunction()
-
-find_external_dependency(MathFunctions)
-
-include ( "${CMAKE_CURRENT_LIST_DIR}/ConsumerTargets.cmake" )

Help/guide/tutorial/Consumer/consumer.cxx

-// A simple function that computes the square root of a number
-#include <iostream>
-#include <sstream>
-#include <string>
-
-#include "MathFunctions.h"
-
-double string_square_root(std::string const& value)
-{
-  return mathfunctions::sqrt(std::stod(value));
-}