some limits

Because of the AGAL limit,the system has these limits:

• the AGAL only allows max 200 line opcodes in a shader,so the action’s count is limited.
• the AGAL only provides 8 va,the local action is the very limited.
• The max VertexBuffer3D’s length agal allow is 65535,so the vertices of all particles’ sum must be less than 65535.