Update TileMeshQuadGridBehaviour.cs

[rakkarage]

getting the uv list from the mesh each time you set a tile makes a new copy of the list each time and in profiler it spikes gc often if setting tiles often

storing it removes all gc

thanks

[alexanderfast]

Isn't _uv always null? It seems to never be assigned.

[aggsol]

In line 50 of CreateMesh() the array for _uv is created.