started pair of transition derivatives

These will serve as stock transitions and as a reference implementation for
hardware accelerated transitions.

app/node/block/transition/diptoblack/CMakeLists.txt

@@ -0,0 +1,22 @@
+# Olive - Non-Linear Video Editor
+# Copyright (C) 2019 Olive Team
+#
+# This program is free software: you can redistribute it and/or modify
+# it under the terms of the GNU General Public License as published by
+# the Free Software Foundation, either version 3 of the License, or
+# (at your option) any later version.
+#
+# This program is distributed in the hope that it will be useful,
+# but WITHOUT ANY WARRANTY; without even the implied warranty of
+# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+# GNU General Public License for more details.
+#
+# You should have received a copy of the GNU General Public License
+# along with this program.  If not, see <http://www.gnu.org/licenses/>.
+
+set(OLIVE_SOURCES
+  ${OLIVE_SOURCES}
+  node/block/transition/diptoblack/diptoblack.h
+  node/block/transition/diptoblack/diptoblack.cpp
+  PARENT_SCOPE
+)

app/node/block/transition/diptoblack/diptoblack.cpp

@@ -0,0 +1,6 @@
+#include "diptoblack.h"
+
+DipToBlackTransition::DipToBlackTransition()
+{
+
+}

app/node/block/transition/diptoblack/diptoblack.h

@@ -0,0 +1,12 @@
+#ifndef DIPTOBLACKTRANSITION_H
+#define DIPTOBLACKTRANSITION_H
+
+#include "../transition.h"
+
+class DipToBlackTransition : public TransitionBlock
+{
+public:
+  DipToBlackTransition();
+};
+
+#endif // DIPTOBLACKTRANSITION_H