Add function get_cwd and function calc.

get_cwd returns the current working directory.
calc returns RankList which have scores added.
Update some comments and format.
Update SVMRanker to be compatible with new APIs.

Remove get_cwd function. Implement calc function. Leave rank function in TO-DO
state.
Clean up include files and update copyright statement.
Add create_ranklist function without arguments.
Clean up unnecessary code.

Update format and copyright statement.
Use new APIs of FeatureManager and Ranker.