GUI: serialization refactoring part 7

The the rest of classes have got readFrom and writeTo methods.

Serialization of instruments is done.

The rest of work is to remove all usages and mentions of serialization.

GUI/Model/Device/BackgroundItems.cpp

@@ -14,6 +14,7 @@
 
 #include "GUI/Model/Device/BackgroundItems.h"
 #include "GUI/Support/XML/Serialize.h"
+#include "GUI/Support/XML/UtilXML.h"
 #include "Sim/Background/ConstantBackground.h"
 #include "Sim/Background/PoissonBackground.h"
 
@@ -38,8 +39,40 @@ std::unique_ptr<IBackground> ConstantBackgroundItem::createBackground() const
 
 void ConstantBackgroundItem::serialize(Streamer& s)
 {
-    s.assertVersion(0);
-    Serialize::rwProperty(s, Tag::BackgroundValue, m_backgroundValue);
+//    s.assertVersion(0);
+//    Serialize::rwProperty(s, Tag::BackgroundValue, m_backgroundValue);
+    if (s.xmlReader())
+        readFrom(s.xmlReader());
+    else if (s.xmlWriter())
+        writeTo(s.xmlWriter());
+}
+
+void ConstantBackgroundItem::writeTo(QXmlStreamWriter *w) const
+{
+    XML::writeAttribute(w, XML::Attrib::version, uint(1));
+
+    // background value
+    w->writeStartElement(Tag::BackgroundValue);
+    m_backgroundValue.writeTo(w);
+    w->writeEndElement();
+}
+
+void ConstantBackgroundItem::readFrom(QXmlStreamReader *r)
+{
+    const uint version = XML::readUIntAttribute(r, XML::Attrib::version);
+    Q_UNUSED(version)
+
+    while (r->readNextStartElement()) {
+        QString tag = r->name().toString();
+
+        // background value
+        if (tag == Tag::BackgroundValue) {
+            m_backgroundValue.readFrom(r);
+            XML::gotoEndElementOfTag(r, tag);
+
+        } else
+            r->skipCurrentElement();
+    }
 }
 
 std::unique_ptr<IBackground> PoissonBackgroundItem::createBackground() const