Initial support for P4 #276

Job	Run time
Check MSRV (x86_64-unknown-linux-gnu)	33s
Check lib (x86_64-unknown-linux-gnu)	35s
Check MSRV (aarch64-unknown-linux-gnu)	1m 38s
Clippy (x86_64-unknown-linux-gnu)	1m 23s
Check lib (aarch64-unknown-linux-gnu)	2m 27s
Check (x86_64-apple-darwin)	31s
Check MSRV (armv7-unknown-linux-gnueabihf)	3m 11s
Clippy (aarch64-unknown-linux-gnu)	1m 53s
Check lib (armv7-unknown-linux-gnueabihf)	1m 12s
Check (x86_64-unknown-linux-gnu)	27s
Check (x86_64-unknown-linux-musl)	51s
Clippy (armv7-unknown-linux-gnueabihf)	1m 27s
Check (x86_64-pc-windows-msvc)	3m 20s
Rustfmt	20s
Unit Tests (x86_64-unknown-linux-gnu)	46s
Check (aarch64-unknown-linux-gnu)	3m 5s
Unit Tests (aarch64-unknown-linux-gnu)	1m 37s
Check (armv7-unknown-linux-gnueabihf)	1m 38s
Unit Tests (armv7-unknown-linux-gnueabihf)	1m 34s
	28m 28s

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