ngram command has a subcommand, which is named "build", used to construct a LM.
ngram command has a subcommand, which is named "run", used to start a server for word completion.
Cosme: Capitalize the first words of "usages" for subcommands.
Assign the short names to subcommands properly.
"Build" subcommand requires three arguments: N-gram order, the output path of model and the input paths of training corpora.
"Run" subcommand requires one argument: the path of a model used for completion and scoring.
Avoid using of-attachment to the NP including "of".
Implement command-line interface.
Merge branch 'feature/command-interface'