RadixN: Like Radix4, but supports size 2,3,4,5,6, and 7 cross-FFTs all in the same instance #279

Job	Run time
Check and test Linux arm 64bit with neon (stable)	1m 53s
Check+Test no features (stable)	32s
Check and test WebAssembly with SIMD (stable)	1m 2s
Check and test Linux arm 64bit with neon (beta)	1m 50s
Check+Test default features (stable)	1m 24s
Check+Test no features (beta)	40s
Check and test WebAssembly with SIMD (beta)	1m 3s
Check and test Linux arm 64bit with neon (nightly)	1m 48s
Check+Test default features (beta)	1m 23s
Check+Test no features (nightly)	39s
Check and test WebAssembly with SIMD (nightly)	1m 4s
Check and test Linux arm 64bit with neon (1.61)	4m 4s
Check+Test default features (nightly)	1m 26s
Check+Test no features (1.61)	2m 48s
Check and test WebAssembly with SIMD (1.61)	3m 13s
Check+Test default features (1.61)	2m 52s
Check and test Linux x86 32bit	1m 35s
Rustfmt	14s
	29m 30s

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