Not a big deal, but use string= here instead of equal
Rename an argument to `boiled-mozc-start-conversion'

Give it a better name because it doesn't need to be a vector.
While I'm at it, give the docstring a better description.
Eliminate no longer necessary vconcat calls
Reword the docstring of `boiled-mozc-smart-trailing-n'
Do nothing when there's no Romaji strip to be converted

Before this commit, such a situation caused an error.
Simply use the saved strip for cyclic conversion to Romaji(Hankaku)

Calling `japanese-hankaku-region' followed by `japanese-zenkaku-region'
doesn't result in an original string in some cases; e.g., '.' and ','.
Bump the version to 0.5