Enable coverage testing

Use --enable-coverage and make coverage to get it.
Remove Makefile.decl

We are now using glib-tap.mk for the tests, and all we gain
from Makefile.decl is a predefined EXTRA_DIST, which doesn't
seem worth it.
One forgotten instance of Makefile.decl
Two more instances of Makefile.decl
Declare the removal of Makefile.decl complete
Visual Studio Projects: Split the Property Sheets

Split up the Visual Studio 2008/2010 property sheets, so that they can be
more easily maintained; also remove items that aren't really needed for the
build and merge a few items that are frequently repeated.

Also make the copying of config.h from config.h.win32 done with a custom
build rule so that we have a clean source tree when cleaning the build from
the IDE.
qtif: fix fread() error check

fread() doesn't return -1 on error, so don't check for < 0.

https://bugzilla.gnome.org/show_bug.cgi?id=721371
Update glib-tap.mk from glib

This will let us use tap mode for installed tests as well.
Merge branch 'master' of git://git.gnome.org/gdk-pixbuf