Add generic templates (#307)

- Add generic full-page templates.  (This feature from 3.4 was missing)
- Also add generic half-page, quarter-page, and envelope templates.
- Add several more common envelope sizes to page-sizes.xml
- Qt print backend does not need pwg_size.
    - Replace with pwg_class, to distinguish between ISO and NA sizes

model/Paper.hpp

@@ -32,13 +32,23 @@ namespace glabels::model
 
         class Paper
         {
+        public:
+                enum Type
+                {
+                        SHEET,
+                        ENVELOPE,
+                        ROLL
+                };
+
+
         public:
                 Paper() = default;
                 Paper( const QString& id,
                        const QString& name,
                        Distance       width,
                        Distance       height,
-                       const QString& pwgSize );
+                       const QString& pwgClass,
+                       Type           type = SHEET );
                 ~Paper() = default;
 
                 QString id() const;
@@ -50,18 +60,23 @@ namespace glabels::model
                 /* Height */
                 Distance height() const;
 
-                /* PWG 5101.1-2002 size name */
-                QString pwgSize() const;
+                /* PWG 5101.1-2023 class */
+                QString pwgClass() const;
+
+                Type type() const;
 
                 bool isSizeIso() const;
                 bool isSizeUs() const;
 
+
         private:
                 QString  mId;
                 QString  mName;
                 Distance mWidth;
                 Distance mHeight;
-                QString  mPwgSize;
+                QString  mPwgClass;
+                Type     mType;
+
         };
 
 }