Fix for #48 (items duping upon assembly/disassembly)

[aphom]

Rudimentary fix for items duping upon assembly and disassembly.

Closes #48, closes Creators-of-Aeronautics/Simulated-Project#315, closes Creators-of-Aeronautics/Simulated-Project#329, closes Creators-of-Aeronautics/Simulated-Project#94

The old blocks that were being assembled / disassembled are first temporarily replaced by barriers to prevent brittle blocks from breaking prematurely, then they are replaced by air to complete the assembly / disassembly, which fixes the issue with certain items duping.

Before the fix is applied:

After the fix is applied:

[CLAassistant]

All committers have signed the CLA.

[aphom]

There are still issues with these blocks listed below that allow placement of brittle blocks, as they also have the "wrench_pickup" tag, so they mess up the sorting because they are included in the list of brittle blocks.. so the dupe bug still happens with them. Not sure how to fix this as of right now without manually making a specific list of blocks that should be excluded from the brittle blocks list, which would probably not be feasible because of other addons' blocks.

• Redstone Lamp, Target Block, Observer, Hopper, Pistons, Daylight Detector, Cart Assembler, Block of Industrial Iron, Block of Weathered Iron, Andesite Bars, Brass Bars, Copper Bars

From some testing it seems that these blocks mostly have issues while disassembling.

*This is no longer an issue with the new fix implementation.

[aphom]

With the new version of the fix, the issue with those select blocks that were mentioned previously no longer happens. Physics contraptions assemble and disassemble normally, without item duping.