fix mapboxgl下模块和common下模块重名的问题。

Author: caoxinke@supermap.com

src/mapboxgl/overlay/theme/index.js

@@ -1,4 +1,4 @@
 export {GeoFeature} from './GeoFeatureThemeLayer'
 export {Theme3DLayer} from './Theme3DLayer'
 export {ThemeFeature} from './ThemeFeature'
-export {Theme} from './ThemeLayer'
+export {Theme as ThemeLayer} from './ThemeLayer'