Modernize: combined PR

.gitignore

@@ -0,0 +1,6 @@
+Makefile
+build
+CMakeLists.txt.user
+A.1.ele
+A.1.node
+A.1.poly

CMakeLists.txt

@@ -1,12 +1,17 @@
 cmake_minimum_required(VERSION 3.5)
 project(triangle)
 
+find_package(X11)
+
+if(X11_FOUND)
+  option(BUILD_SHOWME    "Build showme executable" OFF)
+endif()
 option(BUILD_EXECUTABLE "Build triangle executable" OFF)
 option(BUILD_LIBRARY    "Build libtriangle library" ON)
 
 if(BUILD_LIBRARY)
   add_library(triangle STATIC triangle.cpp)
-  target_compile_definitions(triangle PRIVATE -DTRILIBRARY -DANSI_DECLARATORS)
+  target_compile_definitions(triangle PRIVATE -DTRILIBRARY)
   if(WIN32)
     target_compile_definitions(triangle PRIVATE -DNO_TIMER)
   endif()
@@ -17,9 +22,20 @@ endif()
 
 if(BUILD_EXECUTABLE)
   add_executable(triangle_exec triangle.cpp)
-  target_compile_definitions(triangle_exec PRIVATE -DANSI_DECLARATORS)
+  target_compile_definitions(triangle_exec PRIVATE)
   if(WIN32)
     target_compile_definitions(triangle_exec PRIVATE -DNO_TIMER)
   endif()
   set_target_properties(triangle_exec PROPERTIES OUTPUT_NAME triangle)
 endif()
+
+if(X11_FOUND)
+  if(BUILD_SHOWME)
+    include_directories(${X11_INCLUDE_DIR})
+    add_executable(showme_exec showme.cpp)
+    target_compile_definitions(showme_exec PRIVATE)
+    target_link_libraries(showme_exec ${X11_LIBRARIES})
+    set_target_properties(showme_exec PROPERTIES OUTPUT_NAME showme)
+  endif()
+endif()
+