Merge pull request #380 from nortikin/docs-pass-1

Docs pass 1
Merge pull request #381 from nortikin/docs-pass-1

Docs pass 1 (3pt Arc and 2pt spline)
Merge pull request #382 from nortikin/docs-pass-1

Docs pass 1
updating line code
line rst and examples
Merge remote-tracking branch 'origin/master' into docs-pass-1