Adds Additional double action easier mission

Adds double action easier mission 3-6
Adds double action mission 5-8
Reverting Double action easier mission 5

Reverting Double action easier mission 5 that was overwritten in
previous commit.
Adding mission introduction to all double action missions
Adding double action mission 9-12
Ading non abbrevated strings
Merge pull request #7 from tompen/additional4

Adds Additional Double Action missions