Untangle saving TTI files into new file

The saving code is an attempt to be page function and page coding
agnostic so the same code can save (G)POP, (G)DRCS and MOT pages in
the future.

loadsave will be the home of page loading, URL exporting and also for
importing and exporting of other teletext file formats.

document.h

@@ -48,8 +48,8 @@ public:
 //	void setPacketCoding(PacketCodingEnum);
 
 	void loadDocument(QFile *);
-	void saveDocument(QTextStream *);
 	int numberOfSubPages() const { return m_subPages.size(); }
+	LevelOnePage* subPage(int p) const { return m_subPages[p]; }
 	LevelOnePage* currentSubPage() const { return m_subPages[m_currentSubPageIndex]; }
 	int currentSubPageIndex() const { return m_currentSubPageIndex; }
 	void selectSubPageIndex(int, bool=false);