Port ruby data_generator.rb to Julia (#258)

Port ruby data_generator.rb to Julia (#258)

* Port ruby data_generator.rb to Julia

This reduces the number of dependencies needed when regenerating the C
code. The new code also separates C code generation from unicode data
analysis somewhat more cleanly which should be better factored for
generating a Julia version of the data files in the future.

The output is identical to the original Ruby script, for now. Some bugs
which were found in the process are noted as FIXMEs in the Julia source
and can be fixed next.

* Replace some explicit loops with a utility function

* fixup! Port ruby data_generator.rb to Julia

* Update Makefile

* Update data/Makefile

* Update data/Makefile

* Update data/Makefile

* Update data/Makefile

* Update data/data_generator.jl

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Co-authored-by: Steven G. Johnson <stevenj@mit.edu>