Add Maneuver Planner module to easily create standard maneuvers

[allista]

Including multi-patch and multi-node maneuvers.

Obvious candidates are:

• [ ] circularize (at PeA, ApA, specific UT, specific R)
• [ ] change PeA, ApA
• [ ] change Inclination, including milti-maneuver gradual shift for low-TMR vessels
• [ ] slingshot - out of planet's SOI using one of its moons
• [ ] to moon = slingshot with specified PeA + circularization at PeA
• [ ] from moon - 1-maneuver retrograde to moon's orbit to drop orbital energy and achieve the desired PeA around parent planet
• [ ] to other planet or its moon - the whole program with a starting slingshot (if possible), inclination change, hohmann transfer and all