Improve performance

[Rushmead]

Currently the way that lights work is that every x amount of ticks it raytraces using the current pan / tilt to calculate the position for the light block to be placed.

It does this regardless of whether or not the light is powered or whether not it has actually moved. This should be changed so that it is only ray-tracing when powered and when there is a neighbouring block update to the illuminator block.

The light block (Illuminator) is also a ticking TileEntity, originally so that it can detect if the fixture creating the light has been destroyed. This is bad and could potentially cause performance problems. A solution is to have the block "decay" using block state and block updates, if the "decay" is 0, the block destroys itself. The fixture emitting the light should regularly update this "decay" value in order for the light to stay.

[Rushmead]

I have done the initial pass of this, see a7cdb87, however I can see some potential issues with this.

[FreneticScribbler]

Course, the biggest performance monster is likely all the lighting updates the illuminators generate, unless modern MC has fixed that being a lagfest?