Add cmake + native windows support for asymptote, with fully working make support #17

Job	Run time
determine_version_suffix	5s
build-gui / build-gui-linux	10s
build-gui / build-gui-windows	41s
build-asy-windows / configure-windows-msvc-x64	2m 10s
build-asy-linux / configure-linux-release-x64	50s
build-asy-linux / build-linux-release-x64	1m 31s
build-asy-windows / build-windows-msvc-x64	6m 26s
build-asy-linux / linux-asy-docgen	2m 16s
build-asy-linux / package-asymptote-artifacts	13s
test-asy-linux / test-x64-asy-tests	26s
test-asy-linux / test-x64-cxxtests	25s
package-asy-install-file / package-asy-installer	40s
test-asy-windows / test-windows-msvc-x64-cxxtests	32s
test-asy-windows / test-windows-msvc-x64-asy-tests	37s
precheck-pass	1s
	17m 3s

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