build: fix automake warning about preprocessor C flags

With automake version 1.13.2 (which comes in debian testing/jessie),
we were starting to get these warnings by default:

...
Running automake --foreign  ...
atk/glue/Makefile.am:16: warning: 'INCLUDES' is the old name for 'AM_CPPFLAGS' (or '*_CPPFLAGS')
gio/glue/Makefile.am:11: warning: 'INCLUDES' is the old name for 'AM_CPPFLAGS' (or '*_CPPFLAGS')
gtk/glue/Makefile.am:18: warning: 'INCLUDES' is the old name for 'AM_CPPFLAGS' (or '*_CPPFLAGS')
gtk/gui-thread-check/profiler/Makefile.am:8: warning: 'INCLUDES' is the old name for 'AM_CPPFLAGS' (or '*_CPPFLAGS')
pango/glue/Makefile.am:13: warning: 'INCLUDES' is the old name for 'AM_CPPFLAGS' (or '*_CPPFLAGS')
sample/opaquetest/Makefile.am:18: warning: 'INCLUDES' is the old name for 'AM_CPPFLAGS' (or '*_CPPFLAGS')
sample/valtest/Makefile.am:18: warning: 'INCLUDES' is the old name for 'AM_CPPFLAGS' (or '*_CPPFLAGS')
Running autoconf ...
...

We simply follow the warning's recommendation of using AM_CPPFLAGS instead
(CPP meaning C PreProcessor, not C Plus Plus), as explained in
http://www.gnu.org/software/automake/manual/html_node/Program-Variables.html

The deprecation of INCLUDES has been very long there already (since 2002,
therefore Automake 1.7), and we already depend on automake 1.10.
glib: avoid a delegate to be GCed which caused a NRE (bxc#13113)

What seemed to be a race condition (because of not happenning 100% of
the times) ended up being an early garbage collection of a delegate that
was still referenced by an unmanaged struct without having a managed
counterpart [1].

The consequence of this was a NullReferenceException happening in a line
which didn't have a dereference of a null object. The way to reproduce it
deterministically 100% of the times was setting the env var MONO_NO_SMP.

[1] http://www.mono-project.com/Interop_with_Native_Libraries#Memory_Boundaries
Merge pull request #63 from knocte/class_init

glib: avoid a delegate to be GCed which could cause a NRE (bxc#13113)
Merge pull request #62 from knocte/automake_warnings

build: fix automake warning about preprocessor C flags
generator: generate all interfaces with the "I" prefix (.NET convention)

To be able to do this, Name property of GenBase class is now virtual, so
that it can be overriden in InterfaceGen with the new name.

Adapters, however, are still classes and then need special care as such
(cannot use the 'Name' property anymore), but this improves a bit the
readability of some parts of the code as the *Implementor and *Adapter
suffixes are now concentrated in just two new properties of GenBase and
not repeated all over the place.
gio: Track API changes (I- interface prefixes)

This includes changes to fix the build, and changes to custom code that
gets added to the generated code. I.e. File.cs now becomes IFile.cs
gtk: Track API changes (I- interface prefixes)

This includes changes to fix the build, and changes to custom code that
gets added to the generated code. I.e. TreeModel now becomes ITreeModel
samples: Track API changes (I- interface prefixes)

This includes changes to fix the build.
Merge remote-tracking branch 'mono/master'