Adds constructors in struct ENV_NAV2D_CONFIG and ENVNAV2D and sets the contained pointers to NULL.

Prevents the destructor from using wild pointers for deletion.
Updated the environment API to support lazy and egraph planners. Added a LazyARA* planner.
Merge pull request #21 from robotman0/dev

Updated the environment API to support lazy and egraph planners. Added LazyARA*.
Bug fix in LazyARA. It also now fully supports the planner API.
Merge pull request #22 from robotman0/dev

Bug fix in LazyARA. It also now fully supports the planner API.
Merge pull request #23 from sbpl/master

Merge of master into dev
Merge pull request #24 from sbpl/dev

Merge of dev into master
bump version to 1.2.0
Merge branch 'master' of https://github.com/sbpl/sbpl