Unified implementation of filters for CloneSources

All filters now derive from FrameBufferFilter, which is always used in a CloneSource. Default FrameBufferFilter is Passthrough filter. Others are Delay and Image filters. Implemented UI selection of filter type, XML session save and load. Linked ImageFilter to Code editor.

FrameBufferFilter.cpp

@@ -0,0 +1,47 @@
+#include "FrameBuffer.h"
+#include "Resource.h"
+#include "Visitor.h"
+
+#include "FrameBufferFilter.h"
+#include "FrameBufferFilter.h"
+
+const char* FrameBufferFilter::type_label[FrameBufferFilter::FILTER_INVALID] = {
+    "None", "Delay", "Custom"
+};
+
+FrameBufferFilter::FrameBufferFilter() : enabled_(true), input_(nullptr)
+{
+
+}
+
+void FrameBufferFilter::draw (FrameBuffer *input)
+{
+    input_ = input;
+}
+
+void FrameBufferFilter::accept(Visitor& v)
+{
+    if (input_)
+        v.visit(*this);
+}
+
+PassthroughFilter::PassthroughFilter() : FrameBufferFilter()
+{
+
+}
+
+uint PassthroughFilter::texture() const
+{
+    if (input_)
+        return input_->texture();
+    else
+        return Resource::getTextureBlack();
+}
+
+glm::vec3 PassthroughFilter::resolution() const
+{
+    if (input_)
+        return input_->resolution();
+    else
+        return glm::vec3(1,1,0);
+}