Remove Table and other deprecated classes.

* docs/tutorial/C/gtkmm-tutorial-in.xml: Remove the description of Table.
Replace Table by Grid. Replace the deprecated HX and VX classes (HBox etc.)
by the corresponding X classes (Box etc.).
* docs/tutorial/C/figures/table.png: Deleted screenshot
* docs/tutorial/Makefile.am: Don't mention the deleted file.
* examples/book/assistant/examplewindow.[h|cc]:
* examples/book/clipboard/ideal/examplewindow.[h|cc]:
* examples/book/clipboard/simple/examplewindow.[h|cc]:
* examples/book/printing/advanced/examplewindow.[h|cc]:
* examples/book/printing/simple/examplewindow.[h|cc]:
* examples/book/progressbar/examplewindow.[h|cc]:
* examples/book/scrolledwindow/examplewindow.[h|cc]:
* examples/others/arrow/direction.cc:
* examples/others/dnd/dndwindow.[h|cc]:
* examples/others/tictactoe/tictactoe.cc: Replace Table by Grid.
* examples/book/drawingarea/joins/myarea.cc: Remove unused variable.
* examples/others/cellrenderercustom/cellrenderertoggle.cc: Use all variables.
* examples/book/table: Delete directory and all files in it.
* examples/Makefile.am: Don't mention the deleted files.