Add CMake support

CMakeLists.txt

@@ -0,0 +1,37 @@
+cmake_minimum_required(VERSION 3.8)
+
+project(leaf VERSION 0.2.1 LANGUAGES CXX)
+
+add_library(leaf INTERFACE)
+target_sources(leaf INTERFACE 
+               $<BUILD_INTERFACE:${ARG_SOURCES}>)
+
+target_include_directories(leaf INTERFACE
+ $<BUILD_INTERFACE:${CMAKE_CURRENT_SOURCE_DIR}/include>
+ $<INSTALL_INTERFACE:include>
+)
+
+include(CMakePackageConfigHelpers)
+write_basic_package_version_file(
+  "${PROJECT_BINARY_DIR}/leaf-config-version.cmake"
+  COMPATIBILITY SameMajorVersion
+)
+
+include(GNUInstallDirs)
+install(TARGETS leaf
+  EXPORT leaf-targets
+  INCLUDES DESTINATION ${CMAKE_INSTALL_INCLUDEDIR}
+)
+
+install(EXPORT leaf-targets
+  FILE
+    leaf-config.cmake
+  NAMESPACE
+    zajo::
+  DESTINATION
+    ${CMAKE_INSTALL_DATADIR}/cmake/leaf
+)
+
+install(FILES "${PROJECT_BINARY_DIR}/leaf-config-version.cmake"
+        DESTINATION ${CMAKE_INSTALL_DATADIR}/cmake/leaf)
+install(DIRECTORY ${PROJECT_SOURCE_DIR}/include/ DESTINATION ${CMAKE_INSTALL_INCLUDEDIR})