Implement I/O safety traits #488

Job	Run time
Clippy	17s
Docs	4s
CheckTargets	1m 20s
Check (aarch64-apple-ios)	32s
MinimalVersions (ubuntu-latest)	18s
MSRV (ubuntu-latest)	13s
MinimalVersions (macos-latest)	35s
MSRV (macos-latest)	16s
MinimalVersions (windows-latest)	43s
Nightly	21s
MSRV (windows-latest)	33s
Check (aarch64-apple-tvos)	33s
Check (aarch64-unknown-openbsd)	33s
Rustfmt	6s
Check (arm64_32-apple-watchos)	32s
Sanitizer (address)	42s
Test (ubuntu-latest)	43s
Check (armv7-sony-vita-newlibeabihf)	30s
Sanitizer (leak)	39s
Test (macos-latest)	51s
TestPoll	26s
Sanitizer (memory)	1m 4s
Check (sparcv9-sun-solaris)	29s
Test (windows-latest)	2m 17s
Sanitizer (thread)	41s
Check (x86_64-pc-solaris)	29s
TestWakerPipe	25s
Check (x86_64-unknown-dragonfly)	31s
Check (x86_64-unknown-openbsd)	29s
Passed	1s
	17m 13s

Provide feedback