Detecting typos/errors in command-line options

[hiroshinoji]

It is desirable to output errors or warnings when some unsupported arguments or wrong value for some key is given. For example, ccg eats kBest option, but it is desirable when a user instead gives kbest option. Also, some options only accept a value in some tuple. For example, the dictionary option in kuromoji, which now I'm implementing, would only accept possible values such as ipa, juman, etc. Now a type check works for some options (e.g., Int options), but this mechanism should be extended possibly using enum (now all options except numeric values are string).