Introduce example for a more flexible deserialization

Also make the CoverGenerator themes serializeable
Rest is automatic reformatting.

VocaluxeLib/Xml/CXmlReaderBase.cs

@@ -0,0 +1,61 @@
+using System;
+
+namespace VocaluxeLib.Xml
+{
+    /// <summary>
+    ///     Base class that provides basic methods for reading xml, while the actual XML implementation is still abstract to allow different implementations
+    /// </summary>
+    public abstract class CXmlReaderBase
+    {
+        public abstract bool GetValue(string xPath, out string value, string defaultValue = "");
+        public abstract bool GetAttribute(string xPath, string attribute, out string value);
+
+        public bool TryGetBoolValue(string xPath, out bool value, bool defaultValue = false)
+        {
+            value = defaultValue;
+            string val;
+            return GetValue(xPath, out val) && bool.TryParse(val, out value);
+        }
+
+        public bool TryGetIntValue(string xPath, ref int value, int? defaultValue = null)
+        {
+            string val;
+            bool ok = GetValue(xPath, out val) && int.TryParse(val, out value);
+            if (!ok && defaultValue.HasValue)
+                value = defaultValue.Value;
+            return ok;
+        }
+
+        public bool TryGetFloatValue(string xPath, ref float value)
+        {
+            string val;
+            return GetValue(xPath, out val, value.ToString()) && CHelper.TryParse(val, out value);
+        }
+
+        public bool TryGetEnumValue<T>(string xPath, ref T value) where T : struct
+        {
+            string val;
+            return GetValue(xPath, out val, Enum.GetName(typeof(T), value)) && CHelper.TryParse(val, out value, true);
+        }
+
+        public bool TryGetIntValueRange(string xPath, ref int value, int min = 0, int max = 100)
+        {
+            return TryGetIntValue(xPath, ref value) && value.IsInRange(min, max);
+        }
+
+        /// <summary>
+        ///     Gets a normalized (0&lt;=x&lt;=1) float value
+        /// </summary>
+        /// <param name="xPath"></param>
+        /// <param name="value"></param>
+        /// <param name="defaultValue"></param>
+        /// <returns>True if exists and is normalized</returns>
+        public bool TryGetNormalizedFloatValue(string xPath, ref float value, float defaultValue = 0)
+        {
+            bool ok = TryGetFloatValue(xPath, ref value) && value.IsInRange(0f, 1f);
+            if (!ok)
+                value = defaultValue;
+            return ok;
+        }
+    }
+}