Revamp type descriptors #247

Job	Run time
conda (ubuntu, conda-forge, stable)	1m 10s
static builds (ubuntu-latest, stable)	1m 13s
conda (windows, conda-forge, stable)	2m 54s
rustfmt	1m 42s
Address sanitizer	1m 25s
static builds (windows-latest, stable-msvc)	6m 12s
conda (macos, conda-forge, stable)	2m 10s
static builds (windows-latest, stable-gnu)	5m 0s
test apt (stable)	1m 9s
test apt (beta)	58s
static builds (macos-11, stable)	4m 50s
test apt (nightly)	54s
static builds (macos-latest, stable)	2m 44s
	32m 21s

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