Increase the shape vertex count limit

[pdavidc]

Increase the limit on path and polygon vertex count currently imposed on applications. Currently, the following limitations apply to path and polygon shapes:

• Maximum of 65,535 vertices for path/polygon
• Maximum of 32,767 vertices for extruded path/polygon

These limits include the intermediate points added by path and polygon according to the maximumIntermediatePoints property. This limit is a function of the unsigned short data type used to store shape index buffers. Standard OpenGL ES 2 does not provide a larger index data type, but a widely available extension does: https://www.khronos.org/registry/gles/extensions/OES/OES_element_index_uint.txt

Modify shapes to use the GL extension OES_element_index_uint when it's available, thereby increasing the limit on vertex count as follows:

• Maximum of 4,294,967,295 vertices for path/polygon
• Maximum of 2,147,483,647 vertices for extruded path/polygon