Add further data sets

[nilshg]

To add at a minimum:

• Basque data
• California smoking
• German unification

@azev77

[azev77]

• [x] Basque Terrorism, Abadie and Gardeazabal, AER, 2003, (1960-, annual, GDP per capita)
• [x] California Tobacco Control, Abadie, Diamond, Hainmueller, JASA, 2010, (Cigarette Sales, annual, 1988)
• [x] German reunification, Abadie, Diamond, Hainmueller, AJPS, 2015, (GDP, West Germany, 1990)

Also datasets w 1 multiple treated units 2 staggered adoption: mult treated time periods

Other: Mariel Boatlift, Card, 1990 (in Doudchenko Imbens), SCM by Peri & Yasenov, 2015. NJ-PA Minimum Wage, Card & Krueger, 1994, 321 treated units, 1 treatment period Cavallo, Galiani, Noy, Pantano, 2013: Natural Disasters & Economic Growth. Multiple treated units. Multiple time periods. GSynth: Election day turnout. Multiple treated units. Multiple time periods. AugSynth: Kansas Tax Cuts, & Collective Bargaining (multiple treated, staggered adoption) Gobillon, Magnac, RES 2016: Local enterprise zone on French unemployment.