Add cmake + native windows support for asymptote, with fully working make support #65

Job	Run time
determine_asy_version	6s
build-gui / build-gui-windows	43s
build-asy-windows / configure-windows-msvc-x64	6m 32s
build-asy-linux / configure-linux-release-x64	44s
build-gui / build-gui-linux	11s
build-asy-linux / build-linux-release-x64	0s
build-asy-linux / linux-asy-docgen	0s
build-asy-linux / package-asymptote-artifacts	0s
test-asy-linux	0s
build-asy-windows / build-windows-msvc-x64	10m 47s
package-asy-install-file	0s
test-asy-windows / test-windows-msvc-x64-cxxtests	40s
test-asy-windows / test-windows-msvc-x64-asy-tests	53s
precheck-pass	0s
	20m 36s

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