Fix missing PATH= in vmtk_env.sh.in.
Make all endcaps methods work with cellentityidsarray and interactive.

The methods annular and concaveannular now works with interactive mode.
All methods now copy cellentityidsarray from input consistently.
All methods now mark new endcaps in cellentityidsarray.

Annular modes pair the interactively provided boundary ides
automatically, making the input robust for interactive use.
Merge pull request #78 from martinal/entityids-forall-endcapping-methods

Entityids forall endcapping methods