This depends on Change 99078 to function correctly, please merge that first.

This depends on Change 99078 to function correctly, please merge that first.

Place marker view objects above all other map labels

 - There is a known issue where markers are temporarily incorrectly sized after
   changing map styles
 - Use 'sdk-point-overlay' style for markers
 - Remove the 'texture' parameter from 'sdk-point-overlay' at scene load time
   so that custom bitmaps can be used instead of the sprite sheet
 - Clean up the tangram_view_type enum
 - Use 'setMapType' in 'TangramView::create' to start loading the initial scene

Change-Id: Ie5a15448e0dd86463d565f014f7c9de543707735