Create DivesiteImportDialog to select sites to import

Creates the dialog box to select which sites to import from the file
selected in mainwindow.cpp. The DivesiteImportModel is created as a
table to display and select which sites are to be imported. Once the
sites are selected, the Command::importDiveSites command is called to
add the sites to the core dive site table with undo/redo functions.

Signed-off-by: Doug Junkins <junkins@foghead.com>

qt-models/CMakeLists.txt

@@ -29,6 +29,8 @@ set(SUBSURFACE_DESKTOP_MODELS_LIB_SRCS
 	divepicturemodel.h
 	diveplannermodel.cpp
 	diveplannermodel.h
+	divesiteimportmodel.cpp
+	divesiteimportmodel.h
 	divetripmodel.cpp
 	divetripmodel.h
 	filtermodels.cpp