Add external processor support #734

Job	Run time
Check lib (x86_64-unknown-linux-gnu)	33s
Check (x86_64-apple-darwin)	36s
Check lib (aarch64-unknown-linux-gnu)	35s
Check (x86_64-unknown-linux-gnu)	34s
Check lib (armv7-unknown-linux-gnueabihf)	35s
Check (x86_64-unknown-linux-musl)	25s
Check (x86_64-pc-windows-msvc)	27s
Check lib MSRV (x86_64-unknown-linux-gnu)	33s
Check (aarch64-unknown-linux-gnu)	36s
Check lib MSRV (aarch64-unknown-linux-gnu)	35s
Check (armv7-unknown-linux-gnueabihf)	36s
Check lib MSRV (armv7-unknown-linux-gnueabihf)	34s
Unit Tests (x86_64-unknown-linux-gnu)	1s
Clippy (x86_64-unknown-linux-gnu)	33s
Unit Tests (aarch64-unknown-linux-gnu)	33s
Clippy (aarch64-unknown-linux-gnu)	31s
Unit Tests (armv7-unknown-linux-gnueabihf)	35s
Clippy (armv7-unknown-linux-gnueabihf)	34s
Rustfmt	16s
	9m 42s

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