view: Remove overlay

The selection toolbars are no longer on-screen display widgets, so this is
no longer needed.
window: Add overlay on top of stack

This is needed by the notifications.
view: Add method select_all
view: Add select menu button when in selection mode
Add vapi for gd-1.0 instead of building at runtime
Port to GTK+ 3.10
view: Add search button and bar
src/Makefile: Target glib 2.38 and link resources

This is needed for porting widgets to use GTK+ Templates.
window: Port to GTK+ Template
date-entry: Port to GTK+ Template
view: Port to GTK+ Template
view: Add signal search-changed
view: Add new property search-mode-enabled