Add pkgconfig file back to CMake (#225)

Using existing lib3MF.pc.in file, add the necessary CMake rules to
have it built. This requires setting the project version and the
description is just nice. Also required a casing change to match the
generate .so and the pkconfig filename is supposed to match the Name field

CMakeLists.txt

@@ -5,9 +5,6 @@ cmake_policy(SET CMP0048 NEW)
 
 set_property(GLOBAL PROPERTY USE_FOLDERS ON)
 
-project(lib3mf)
-
-
 include(GNUInstallDirs)
 
 # Define Version
@@ -16,6 +13,10 @@ set(LIB3MF_VERSION_MINOR 1)        # increase on every backward compatible chang
 set(LIB3MF_VERSION_MICRO 0)        # increase on on every change that does not alter the API
 set(LIB3MF_VERSION_PRERELEASE "beta")  # denotes pre-release information of a version of lib3mf
 
+project(lib3mf
+  VERSION ${LIB3MF_VERSION_MAJOR}.${LIB3MF_VERSION_MINOR}.${LIB3MF_VERSION_MICRO}
+  DESCRIPTION "An implementation of the 3D Manufacturing Format file standard")
+
 set(CMAKE_INSTALL_BINDIR bin CACHE PATH "directory for installing binary files")
 set(CMAKE_INSTALL_LIBDIR lib CACHE PATH "directory for installing library files")
 set(CMAKE_INSTALL_INCLUDEDIR include/lib3mf CACHE PATH "directory for installing header files")
@@ -190,6 +191,8 @@ else()
   target_compile_options(${PROJECT_NAME} PUBLIC "$<$<CONFIG:RELEASE>:/O2;/sdl;/WX;/Oi;/Gy;/FC;/wd4996>")
 endif()
 
+configure_file(lib3mf.pc.in lib3mf.pc @ONLY)
+install(FILES ${CMAKE_BINARY_DIR}/lib3mf.pc DESTINATION ${CMAKE_INSTALL_LIBDIR}/pkgconfig)
 install(TARGETS ${PROJECT_NAME}
   ARCHIVE DESTINATION "${CMAKE_INSTALL_LIBDIR}"
   LIBRARY DESTINATION "${CMAKE_INSTALL_LIBDIR}"

lib3mf.pc.in

@@ -0,0 +1,12 @@
+prefix=@CMAKE_INSTALL_PREFIX@
+exec_prefix=@CMAKE_INSTALL_PREFIX@
+libdir=${exec_prefix}/@CMAKE_INSTALL_LIBDIR@
+includedir=${prefix}/@CMAKE_INSTALL_INCLUDEDIR@
+
+Name: @PROJECT_NAME@
+Description: @PROJECT_DESCRIPTION@
+Version: @PROJECT_VERSION@
+
+Requires:
+Libs: -L${libdir} -l3mf -lzip -lz
+Cflags: -I${includedir}