v0.2.0-alpha.1: Optionally remove existing geocode columns

If the geocoder would introduce columns that already exist in the file,
we do one of two things:

1. By default, we exit with an error.
2. If the user passes `--replace`, we strip any column with the same
   name as a geocoding output column, and add the output columns
   normally.

Author: emk

Cargo.lock

@@ -1,6 +1,6 @@
 [package]
 name = "geocode-csv"
-version = "0.1.2"
+version = "0.2.0-alpha.1"
 authors = ["Eric Kidd <git@randomhacks.net>"]
 edition = "2018"