Add cmake + native windows support for asymptote, with fully working make support #76

Job	Run time
determine_asy_version	6s
build-asy-linux / configure-linux-release-x64	43s
build-gui / build-gui-windows	43s
build-gui / build-gui-linux	13s
build-asy-windows / configure-windows-msvc-x64	2m 18s
build-asy-linux / build-linux-release-x64	1m 36s
build-asy-windows / build-windows-msvc-x64	6m 33s
build-asy-linux / linux-asy-docgen	2m 34s
build-asy-linux / package-asymptote-artifacts	13s
test-asy-linux / test-x64-asy-tests	43s
test-asy-linux / test-x64-cxxtests	22s
package-asy-install-file / package-asy-installer	43s
test-asy-windows / test-windows-msvc-x64-cxxtests	58s
test-asy-windows / test-windows-msvc-x64-asy-tests	1m 1s
precheck-pass	1s
	18m 47s

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