AURORA: Add GFF3File::getMutableList()

Return a mutable list within a GFF3File.

No GFF3List methods that can add/remove structs exist yet, though.

src/aurora/gff3file.cpp

@@ -105,6 +105,17 @@ GFF3Struct &GFF3File::getMutableStruct(const GFF3Struct &strct) {
 	return *s->second;
 }
 
+GFF3List &GFF3File::getMutableList(const GFF3List &list) {
+	if (list._parent != this)
+		throw Common::Exception("GFF3: That list does not belong to this GFF3");
+
+	ListMap::iterator l = _lists.find(list.getUID());
+	if (l == _lists.end())
+		throw Common::Exception("GFF3: This GFF3 does not know about that list?!?");
+
+	return l->second;
+}
+
 // --- Loader ---
 
 void GFF3File::load(uint32 id) {

src/aurora/gff3file.h

@@ -93,6 +93,14 @@ class GFF3File : public AuroraFile {
 	 */
 	GFF3Struct &getMutableStruct(const GFF3Struct &strct);
 
+	/** Return a mutable struct.
+	 *
+	 *  Given a read-only list, this returns a reference to a mutable version
+	 *  of the same struct within the GFF3. This means, structs in this mutable
+	 *  version can be removed and now structs added.
+	 */
+	GFF3List &getMutableList(const GFF3List &list);
+
 
 private:
 	/** A GFF3 header. */