added CMakeLists.txt

[gmabey]

A thousand apologies for complicating what I feel is an elegant project -- I do really appreciate the simplicity of it all, including the good-old-fashioned Makefile. For my purposes, I gotta create a .deb, and this is the easiest way I know of: use cmake for the build system.

If you reject this PR I'm not offended at all.

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