Keep the "OK" button in "Import" disabled until a DC is selected

Only call report_dives() for GTK_RESPONSE_ACCEPT in the same dialog.

Signed-off-by: Lubomir I. Ivanov <neolit123@gmail.com>
More cosmetic changes in the "Import" dialog

Renamed the XML button and titles slightly.
Generalized the dialog topmost text to "Choose what to import:".

Signed-off-by: Lubomir I. Ivanov <neolit123@gmail.com>
Make sure windows behind forward dialogs are truly inactive

There are possible bugs when targeting GTK 2.24.10.

When opening the "import XML files" file selector from the "import" dialog
on Ubuntu 12.04, even with gtk_window_set_accept_focus() setting FALSE
to the parent ("import"), it is still possible to click the title bar
and buttons, causing actions. This can trigger undefined behaviour -
e.g. opening multiple "import XML files" dialogs.

While on Windows the situation is more acceptable, on Ubuntu it is also
possible to click the [x] button on the title bar of the parent window,
which will close the parent dialog _with_ the current forward dialog.

Multiple proposed methods in the GTK documentation seem not to function
as expected, such as: gtk_window_set_modal() and gtk_window_set_accept_focus().
Passing the correct parent on dialog creation doesn't seems to help either.

The same problem occurs when selecting a default file from the preferences
dialog.

The proposed portable solution in this patch is to completely disable
the background windows by hiding the titlebar (gtk_window_set_decorated),
disabling child controls (gtk_widget_set_sensitive) and making the window
"transient for" or putting it on top (gtk_window_set_transient_for).

Signed-off-by: Lubomir I. Ivanov <neolit123@gmail.com>
Separate the "Import" menu entry into two menu entries in "File" and "Log"

New entries with icons and shortcut keys in the menus.

"Import XML File" is now using CTRL + I.
Reserve CTRL + E for "Export XML File" if possible.

"Download From Dive Computer" is using CTRL + D and
a GTK_STOCK_GO_DOWN icon.
Added separator below this entry in the "Log" menu.

Note: menu entry callbacks are NULL at this stage.

Signed-off-by: Lubomir I. Ivanov <neolit123@gmail.com>
Remove the XML file selection from the DC download dialog

Renamed "import_dialog" to "download_dialog" and also focused the download
dialog strictly on dive computer functionality. Removed the file button
and "filenames" checks from "download_dialog".

Signed-off-by: Lubomir I. Ivanov <neolit123@gmail.com>
Activate the new separate "Import XML File" functionality

Renamed the function pick_import_files() to import_files()
and added a declaration in "display-gtk.h". The declaration is "extern"
for consistency with download_dialog().

Since the new dialog is a real child off "main_window", we no longer need
some of the calls to gtk_widget_set_sensitive(), gtk_window_set_decorated()
to disable the parent, which previously was the old "Import" combined dialog.

Once the file list is retrieved, attempt to import each file and update
the list via report_dives().

Signed-off-by: Lubomir I. Ivanov <neolit123@gmail.com>

Minor changes to file select box title

Signed-off-by: Dirk Hohndel <dirk@hohndel.org>