pep8: fix new pep8 errors
project: check if values exist before setting caps
gtk 3.14: GtkAligment is deprecated. Margin names have changed.

* replace margin-left with margin-start

https://developer.gnome.org/gtk3/stable/GtkWidget.html#GtkWidget--margin-left

* replace margin-right with margin-end

https://developer.gnome.org/gtk3/3.13/GtkWidget.html#GtkWidget--margin-right

* replace xalign with halign
* replace ypad by margin-start
gtk 3.14: stock buttons have been deprecated

https://developer.gnome.org/gtk3/unstable/GtkButton.html#gtk-button-new-from-stock

* use custom buttons
* replace stock-id with icon-name

https://developer.gnome.org/gtk3/3.13/GtkToolButton.html#GtkToolButton--stock-id
gtk 3.14: remove GtkTreeView rules-hint

https://developer.gnome.org/gtk3/3.13/GtkTreeView.html#GtkTreeView--rules-hint
gtk 3.14: GtkColorButton needs a GdkRGBA color

https://developer.gnome.org/gtk3/unstable/GtkColorButton.html#GtkColorButton--color
gtk 3.14: use GtkBox instead of GtkVBox

Remove H and V from GtkBox, GtkScale, GtkPaned and GtkButtonBox
gtk 3.14: schema has been deprecated use schema-id

https://developer.gnome.org/gio/stable/GSettings.html#GSettings--schema
gtk 3.14: ImageMenuItem has been deprecated in 3.10

https://developer.gnome.org/gtk3/unstable/GtkImageMenuItem.html#gtk-image-menu-item-set-image
gtk 3.14: GtkResizeMode GTK_RESIZE_QUEUE has been deprecated

https://developer.gnome.org/gtk3/unstable/GtkContainer.html#GtkResizeMode
gtk 3.14: remove deprecation from about dialog

* add default response
* set_transient_for in about dialog

    https://developer.gnome.org/gtk3/unstable/GtkWindow.html#gtk-window-set-transient-for

* don't use stock buttons
* remove unneeded close callback
gtk 3.14: remove deprecation from filelisterrordialog
gtk 3.14: fix gdk_window_set_icon_list warning

Fix following warning:
(pitivi:18711): Gdk-WARNING **: gdk_window_set_icon_list: icon too large (512x512)

don't set icon on main window and about dialog, since it prints a size warning
gtk 3.14: more dialogs

* set transient
* don't use stock buttons
gtk 3.14: more padding and margin
gtk 3.14: update icons to new names

ui: use correct gtk menu icon

zoom-fit-best icon name has changed
move icons to top of file for glade. add icon to Document open

move icon declarations to the top
gtk 3.14: overwrite all files with glade. Verify 3.12. Replace GtkTable with GtkGrid