csvs-to-sqlite 0.3

• Mechanism for converting columns into separate tables

  Let's say you have a CSV file that looks like this:

  county,precinct,office,district,party,candidate,votes
  Clark,1,President,,REP,John R. Kasich,5
  Clark,2,President,,REP,John R. Kasich,0
  Clark,3,President,,REP,John R. Kasich,7
  

  (Real example from https://github.com/openelections/openelections-data-sd/blob/ master/2016/20160607__sd__primary__clark__precinct.csv )

  You can now convert selected columns into separate lookup tables using the new
  --extract-column option (shortname: -c) - for example:

  csvs-to-sqlite openelections-data-*/*.csv \
      -c county:County:name \
      -c precinct:Precinct:name \
      -c office -c district -c party -c candidate \
      openelections.db
  

  The format is as follows:

  column_name:optional_table_name:optional_table_value_column_name
  

  If you just specify the column name e.g. -c office, the following table will
  be created:

  CREATE TABLE "party" (
      "id" INTEGER PRIMARY KEY,
      "value" TEXT
  );
  

  If you specify all three options, e.g. -c precinct:Precinct:name the table
  will look like this:

  CREATE TABLE "Precinct" (
      "id" INTEGER PRIMARY KEY,
      "name" TEXT
  );
  

  The original tables will be created like this:

  CREATE TABLE "ca__primary__san_francisco__precinct" (
      "county" INTEGER,
      "precinct" INTEGER,
      "office" INTEGER,
      "district" INTEGER,
      "party" INTEGER,
      "candidate" INTEGER,
      "votes" INTEGER,
      FOREIGN KEY (county) REFERENCES County(id),
      FOREIGN KEY (party) REFERENCES party(id),
      FOREIGN KEY (precinct) REFERENCES Precinct(id),
      FOREIGN KEY (office) REFERENCES office(id),
      FOREIGN KEY (candidate) REFERENCES candidate(id)
  );
  

  They will be populated with IDs that reference the new derived tables.

  Closes #2