cmake update

make examples, playground and tests buildable

tests/CMakeLists.txt

@@ -0,0 +1,21 @@
+file(GLOB SUBDIRS RELATIVE ${CMAKE_CURRENT_SOURCE_DIR} "${CMAKE_CURRENT_SOURCE_DIR}/*")
+
+foreach(SUBDIR ${SUBDIRS})
+    if(IS_DIRECTORY ${CMAKE_CURRENT_SOURCE_DIR}/${SUBDIR})
+        file(GLOB SOURCES "${CMAKE_CURRENT_SOURCE_DIR}/${SUBDIR}/*.cpp" "${CMAKE_CURRENT_SOURCE_DIR}/${SUBDIR}/*.h")
+
+        if(SOURCES)
+            add_executable(${SUBDIR} ${SOURCES})
+
+            target_include_directories(${SUBDIR} PRIVATE ${CMAKE_CURRENT_SOURCE_DIR}/${SUBDIR})
+
+            target_link_libraries(${SUBDIR} qwt)
+            if(NOT QWT_BUILD_TESTS)
+                set_target_properties(${SUBDIR} PROPERTIES
+                    EXCLUDE_FROM_ALL TRUE
+                    EXCLUDE_FROM_DEFAULT_BUILD TRUE  # mainly for Visual Studio
+                )
+            endif()
+        endif()
+    endif()
+endforeach()