feat(encoding): encode usize and isize (#282) #1022

Job	Run time
Test Suite	1m 56s
Clippy	1m 20s
Check rustdoc intra-doc links	32s
Rustfmt	20s
Cross compile (powerpc64-unknown-linux-gnu)	22s
Cross compile (armv7-unknown-linux-gnueabihf)	18s
Cross compile (powerpc-unknown-linux-gnu)	18s
Cross compile (wasm32-unknown-unknown)	19s
Check	1m 39s
	7m 4s

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