Change to "show only buildable" option for projectors

Hi team!

I propose a change to the way the "Show only buildable" option works for Projectors.

Currently with the option selected, buildable blocks are projected as long as the block next to them is at least 1% complete.

When welding by hand (especially on small grids) this can cause incomplete blocks or areas of unbuildable blocks to get covered up by other blocks, which then have to be ground back down to get at the ones underneath.

It's also a big problem when building ships using automated "ship printing" devices, as the device may run out of a certain type of component but not another. For example, it could run out of Motors to complete an internal conveyor system but still have loads of Steel Plate; and so it could go on to weld up the hull over the top of an incomplete conveyor network... and unless you were paying close attention, you may not realise what'd happened until it's too late, whereby the only thing to do is cut the ship apart to get at the incomplete blocks inside it.

Since projections are very difficult to see through, the only way to be sure all blocks in a projected grid get welded to completion is to turn the projector off every few minutes to check what's welded & what isn't, then back on again to carry on working. This can get tedious when welding by hand and can totally disrupt progress if using an automated "ship printer" device.

To remedy the problem, I suggest that buildable blocks only be projected if the block/s that make them buildable are welded to 100% completion.

This could be added as a separate option or to replace the existing "show only buildable" option, as prefered.

Please consider and let's have no more incomplete blocks getting covered up inside ships where we can't see them! Hunting for those things can be a nightmare!

Thanks!