Add EQ DN and EQ AN to Apoapsis maneuver

Extremely useful maneuvers for GTO burns when launching into inclined
orbit.

Also add *.sln (Visual Studio Solution Files) to gitignore.
Merge branch 'dev' of https://github.com/MuMech/MechJeb2 into dev
Merge pull request #446 from Wetmelon/dev

Add EQ DN and EQ AN to Apoapsis maneuver