Completed 16 atoms

	modified:   src/koans/16_atoms.clj
Completed 17 Macros

	modified:   src/koans/17_macros.clj
Completed 18 Datatypes

	modified:   src/koans/18_datatypes.clj
Finished 19 Java Interop

	modified:   src/koans/19_java_interop.clj
Completed 20 Partition :'-(

	modified:   src/koans/20_partition.clj