Merge pull request #1 from esa/master

Getting the latest PyKEP
gtoc7 asteroid added
New constructor overloaded for planet: r,v can be used now
Minor docs improvments and small glitch in lambert solved
quick barker equation implemented
Merge branch 'master' of https://github.com/darioizzo/pykep
Update README.md

Minor grammatical/spelling corrections.
Update main.cpp

Minor spelling/grammatical corrections.
Update _ex1.py

Spelling/grammar corrections.
Update _ex3.py

Grammar/spelling corrections.
Update _ex4.py

Spelling/grammatical corrections. (Including the correction Sundmann -> Sundman.)
Merge pull request #5 from NattyBumppo/patch-1

Update README.md
Merge pull request #6 from NattyBumppo/patch-2

Update main.cpp
Merge pull request #7 from NattyBumppo/patch-3

Update _ex1.py
Merge pull request #8 from NattyBumppo/master

More spelling/grammatical corrections
Update closest_distance.h
get_state added to the low-thrust leg and ic2par exposed
bug fix on get_states()
Bug Fix Neptune Uranus ephs
Neptune-Uranus eph fixed