Make allow to optional doc + allow to install po file directly

CMakeLists.txt

@@ -36,13 +36,17 @@ find_package(KF5 ${KF5_MIN_VERSION} REQUIRED COMPONENTS
     Crash
     Config
     ConfigWidgets
-    DocTools
     GuiAddons
     I18n
     Notifications
     XmlGui
 )
 
+find_package(KF5DocTools ${KF5_MIN_VERSION})
+set_package_properties(KF5DocTools PROPERTIES DESCRIPTION
+    "Tools to generate documentation"
+    TYPE OPTIONAL
+)
 
 set (CMAKE_MODULE_PATH "${CMAKE_MODULE_PATH}" ${CMAKE_SOURCE_DIR}/cmake/modules)
 
@@ -131,6 +135,10 @@ install( FILES kcalcui.rc  DESTINATION ${KDE_INSTALL_KXMLGUI5DIR}/kcalc)
 install( FILES scienceconstants.xml  DESTINATION ${KDE_INSTALL_DATADIR}/kcalc)
 install( FILES kcalcrc.upd  DESTINATION ${KDE_INSTALL_DATADIR}/kconf_update)
 
-add_subdirectory(doc)
+ki18n_install(po)
+if (KF5DocTools_FOUND)
+    kdoctools_install(po)
+    add_subdirectory(doc)
+endif()
 
 feature_summary(WHAT ALL FATAL_ON_MISSING_REQUIRED_PACKAGES)