add a cmakeLists for the book (#374)

* add a cmakeLists for the book to add a project in visual studio so the book can be edited with the code

* remove trailing whitespace

* remove restrictions on MSVC and use a globbing expression in finding the files.  Also add a check to make sure book directory exists which seems to be important on appveyor

* apparently doxygen was updated and the old download script no longer worked

* try a different url for the older download

* use github source tar

.ci/build_doxygen.sh

@@ -3,7 +3,8 @@
 
 set -evx
 
-DOXYGEN_URL="http://doxygen.nl/files/doxygen-1.8.15.src.tar.gz"
+#DOXYGEN_URL="http://doxygen.nl/files/doxygen-1.8.17.src.tar.gz"
+DOXYGEN_URL="https://github.com/doxygen/doxygen/archive/Release_1_8_15.tar.gz"
 cd "${DEPS_DIR}"
 
 if [[ ! -f "${DEPS_DIR}/doxygen/build/bin/doxygen" ]] ; then

CMakeLists.txt

@@ -93,6 +93,10 @@ if(CMAKE_PROJECT_NAME STREQUAL PROJECT_NAME)
         endif()
     endif()
 
+    if (EXISTS book)
+       add_subdirectory(book)
+    endif()
+
     if(NOT CMAKE_VERSION VERSION_LESS 3.9)
         find_package(Doxygen)
         if(Doxygen_FOUND)

book/CMakeLists.txt

@@ -0,0 +1,10 @@
+
+set(
+    book_sources
+    README.md
+    SUMMARY.md
+)
+
+file(GLOB book_chapters RELATIVE ${CMAKE_CURRENT_SOURCE_DIR} chapters/*.md)
+add_custom_target(cli_book SOURCES ${book_sources} ${book_chapters})
+