Refactor machines for multiblock io

[fechan]

It needs to be possible to define a machine that has virtual slots corresponding to actual slots on multiple peripherals, i.e. for the I/O of Create sequenced assembly.

[fechan]

Idea is to have machines inherit from a superclass with the following methods:

• new(slots): Configures the peripherals to be managed by the rest of the superclass' inventory methods. slots is a table that maps from slot names to {peripheral, slot_in_peripheral}
• pushItems(toMachine, fromSlot, [limit], [toSlot]): same as CCTweaked inventory API, but accepting a machine instead of a peripheral
• pullItems(fromName, fromSlot, [limit], [toSlot]) see above
• list() ditto
• getItemDetail(slotName) ditto except slot number is replaced by slot name

[fechan]

We can get rid of peripherals from new altogether since it's only used for slot resolution anyway. So instead of peripheral_idx we just pass in refs to the actual peripheral table.

[fechan]

Done. See https://github.com/fechan/modular-factory/blob/master/drivers/create/sequencedassembly.lua for an example