Move format exports into child classes.

To only export implemented methods.

src/ol/format/geojsonformat.exports

@@ -1 +1,8 @@
 @exportSymbol ol.format.GeoJSON
+@exportProperty ol.format.GeoJSON.prototype.readFeature
+@exportProperty ol.format.GeoJSON.prototype.readFeatures
+@exportProperty ol.format.GeoJSON.prototype.readGeometry
+@exportProperty ol.format.GeoJSON.prototype.readProjection
+@exportProperty ol.format.GeoJSON.prototype.writeFeature
+@exportProperty ol.format.GeoJSON.prototype.writeFeatures
+@exportProperty ol.format.GeoJSON.prototype.writeGeometry

src/ol/format/igcformat.exports

@@ -1 +1,3 @@
 @exportSymbol ol.format.IGC
+@exportProperty ol.format.IGC.prototype.readFeature
+@exportProperty ol.format.IGC.prototype.readFeatures

src/ol/format/jsonformat.exports

@@ -1,7 +0,0 @@
-@exportProperty ol.format.JSON.prototype.readFeature
-@exportProperty ol.format.JSON.prototype.readFeatures
-@exportProperty ol.format.JSON.prototype.readGeometry
-@exportProperty ol.format.JSON.prototype.readProjection
-@exportProperty ol.format.JSON.prototype.writeFeature
-@exportProperty ol.format.JSON.prototype.writeFeatures
-@exportProperty ol.format.JSON.prototype.writeGeometry

src/ol/format/kmlformat.exports

@@ -1,2 +1,6 @@
 @exportSymbol ol.format.KML
 @exportProperty ol.format.KML.prototype.readName
+@exportProperty ol.format.KML.prototype.readFeature
+@exportProperty ol.format.KML.prototype.readFeatures
+@exportProperty ol.format.KML.prototype.readGeometry
+@exportProperty ol.format.KML.prototype.readProjection

src/ol/format/textformat.exports

@@ -1,7 +0,0 @@
-@exportProperty ol.format.Text.prototype.readFeature
-@exportProperty ol.format.Text.prototype.readFeatures
-@exportProperty ol.format.Text.prototype.readGeometry
-@exportProperty ol.format.Text.prototype.readProjection
-@exportProperty ol.format.Text.prototype.writeFeature
-@exportProperty ol.format.Text.prototype.writeFeatures
-@exportProperty ol.format.Text.prototype.writeGeometry

src/ol/format/xmlformat.exports

@@ -1,7 +0,0 @@
-@exportProperty ol.format.XML.prototype.readFeature
-@exportProperty ol.format.XML.prototype.readFeatures
-@exportProperty ol.format.XML.prototype.readGeometry
-@exportProperty ol.format.XML.prototype.readProjection
-@exportProperty ol.format.XML.prototype.writeFeature
-@exportProperty ol.format.XML.prototype.writeFeatures
-@exportProperty ol.format.XML.prototype.writeGeometry