The `__future__` we relied on is now, where the 3 specific things are
all included [since Python 3.0](https://docs.python.org/3/library/__future__.html):
* absolute_import
* print_function
* unicode_literals
* division
These import statements are no-ops and are no longer necessary.
Check whether the value in the "before" column is zero (specifically,
whether the file size in that column is greater than zero since
filesizes are non-negative) before dividing the value in the "after"
column by it.
I am upstreaming this for two reasons:
1. Traditionally I have done this by hand in a spreadsheet program. I would
rather just have a program fix it up for me.
2. Multiple people have asked me about how to produce this sort of graph and I
would just like to document it via a script.
I hope it is useful to others. You use the script by invoking it as:
./csvcolumn_to_scurve <input_file> <before_column> <after_column> [output_file]
