Add multiple grids with color support

As in the issue title, creating multiple grids at the same time and giving them colors to make them unique would be a good enhancement to the current Grid. Like /grid 13 14 yellow and /grid 16 18 purple, the colors will be used to make it easier for humans to find which Grid is used for. When you need to hide a grid, you can just say /grid hide yellow because colors is what makes a Grid unique from other.

[guspolly]

Second the idea of having multiple grids. I like to place torches at every 0,0 and 5,5 but not 0,5 or 5,0, so being able to set up one 10 10 grid with the origin at 0,0 and another at 5,5 would be ideal.