Add cmake + native windows support for asymptote, with fully working make support #52

Job	Run time
determine_asy_version	6s
build-gui / build-gui-windows	39s
build-asy-linux / configure-linux-release-x64	48s
build-gui / build-gui-linux	12s
build-asy-windows / configure-windows-msvc-x64	1m 22s
build-asy-linux / build-linux-release-x64	1m 40s
build-asy-windows / build-windows-msvc-x64	4m 45s
build-asy-linux / linux-asy-docgen	2m 29s
build-asy-linux / package-asymptote-artifacts	13s
test-asy-linux / test-x64-asy-tests	38s
test-asy-linux / test-x64-cxxtests	29s
test-asy-windows / test-windows-msvc-x64-asy-tests	2m 14s
test-asy-windows / test-windows-msvc-x64-cxxtests	1m 8s
package-asy-install-file / package-asy-installer	41s
precheck-pass	0s
	17m 24s

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