use GtkBox instead of H/VBox in widget implementations
use GtkBox instead of H/VBox in core builder files
use GtkBox instead of H/VBox in plugin builder files

also GtkScale in place of HScale while I'm here
replace GtkTable with GtkGrid in some builder files

Many more of these to do, but some of them might be redesigned instead.
fix up some calls to deprecated functions in widget implementations
Remove _BSD_SOURCE from makefiles

This appears to have crept in with something relating to dashboard
(who even remembers dashboard?) about 10 years ago.  glibc headers
have recently started complaining about it, so it's time for it to go.
s/INCLUDES/AM_CPPFLAGS/ and some other stuff
Update gtk versions and such in some builder files
ignore .appdata.xml