Frontend

[saifalharthi]

This PR is just for merging purposes.
It contains code refactoring in the planner , as there are several source files corresponding to its header files.
Also the same goes for the parser/peloton set.

[coveralls]

Coverage remained the same at 0.0% when pulling 8da64cf on saifalharthi:frontend into b6f1239 on cmu-db:frontend.

[coveralls]

Coverage remained the same at 0.0% when pulling d61f8ce on saifalharthi:frontend into b6f1239 on cmu-db:frontend.

[coveralls]

Coverage remained the same at 0.0% when pulling 3dba0fb on saifalharthi:frontend into b6f1239 on cmu-db:frontend.

[coveralls]

Coverage remained the same at 0.0% when pulling bd0a868 on saifalharthi:frontend into b6f1239 on cmu-db:frontend.

[coveralls]

Coverage remained the same at 0.0% when pulling 86b9a15 on saifalharthi:frontend into 3aff639 on cmu-db:frontend.

[coveralls]

Coverage remained the same at 0.0% when pulling c60e8f2 on saifalharthi:frontend into 3aff639 on cmu-db:frontend.

[coveralls]

Coverage remained the same at 0.0% when pulling f3062d1 on saifalharthi:frontend into 3aff639 on cmu-db:frontend.

[coveralls]

Coverage remained the same at 0.0% when pulling 794d41d on saifalharthi:frontend into 3aff639 on cmu-db:frontend.

[coveralls]

Coverage remained the same at 0.0% when pulling 794d41d on saifalharthi:frontend into 3aff639 on cmu-db:frontend.

[coveralls]

Coverage remained the same at 0.0% when pulling c44b682 on saifalharthi:frontend into 3aff639 on cmu-db:frontend.

[coveralls]

Coverage remained the same at 0.0% when pulling 8ee49a2 on saifalharthi:frontend into 3aff639 on cmu-db:frontend.

[coveralls]

Coverage remained the same at 0.0% when pulling 095bc5a on saifalharthi:frontend into 3aff639 on cmu-db:frontend.

[coveralls]

Coverage remained the same at 0.0% when pulling 49ec98e on saifalharthi:frontend into 3aff639 on cmu-db:frontend.