Merge branch 'update-finder-qwt6' into 'master'

Update qwt6 finder to find qwt-qt5 on non-acg debian systems

See merge request !53

cmake/FindQwt6.cmake

@@ -124,7 +124,7 @@ if (QWT6_VERSION_FOUND)
       )
  
     if (NOT QWT6_LIBRARY) # if not the specific acg qwt installation was found, try system wide
-      find_library(QWT6_LIBRARY NAMES qwt
+      find_library(QWT6_LIBRARY NAMES qwt qwt-qt5
         PATHS
         /opt/local/libexec/qt5/lib
         /usr/local/qwt/lib