Add in optimizations for 2^N radix integer writing. #110

Job	Run time
Rust aarch64-linux-android	6m 48s
Rust arm-linux-androideabi	6m 33s
Rust armv7-linux-androideabi	7m 1s
Rust powerpc64-unknown-linux-gnu	1m 42s
Rust i686-linux-android	5m 40s
Rust s390x-unknown-linux-gnu	1m 42s
Rust x86_64-linux-android	5m 9s
Rust i686-unknown-freebsd	1m 45s
Rust aarch64-unknown-linux-gnu	5m 24s
Rust x86_64-unknown-freebsd	1m 46s
Rust arm-unknown-linux-gnueabi	5m 53s
Rust x86_64-unknown-netbsd	1m 51s
Rust armv7-unknown-linux-gnueabihf	5m 43s
Rust mips-unknown-linux-gnu	1m 38s
Rust i686-unknown-linux-gnu	3m 48s
Rust mips64-unknown-linux-gnuabi64	1m 40s
Rust mips64el-unknown-linux-gnuabi64	1m 41s
Rust i686-unknown-linux-musl	3m 52s
Rust mipsel-unknown-linux-gnu	1m 41s
Rust x86_64-unknown-linux-musl	3m 40s
Rust x86_64-pc-windows-gnu	4m 26s
	1h 19m 23s

Provide feedback