Update JMdict/JMnedict titles and Revision for KANJIDIC

[MarvNC]

• Add publication date to titles
• Add revision for KANJIDIC so it can auto-update properly (fun fact, it was last updated Feb this year)
  Resolves Update JMdict/JMnedict titles and Revision for KANJIDIC #23

For example, after this change:

[Kuuuube]

Is there a reason for not having a separate function with some validation for the kanjidic date like jmdict or jmnedict have? Is kanjidic formatted differently to where this is not needed?

func jmdictPublicationDate(dictionary jmdict.Jmdict) string {
	unknownDate := "unknown"
	idx := -1
	for i, entry := range dictionary.Entries {
	jmdictDate := jmdictPublicationDate(dictionary)
        ...

[MarvNC]

Because it's a one-liner as KANJIDIC is indeed formatted differently. For JMdict/JMnedict, the date is in a comment so we need to look at the ＪＭｄｉｃｔ entry for the date, while for KANJIDIC it's in the header so we can just access it.
https://github.com/themoeway/jmdict-go/blob/fa8f5d54f3647f9c24ce6079194cb4b8596bbf7b/kanjidic.go#L13-L25

type KanjidicHeader struct {
	// This field denotes the version of kanjidic2 structure, as more
	// than one version may exist.
	FileVersion string `xml:"file_version"`


	// The version of the file, in the format YYYY-NN, where NN will be
	// a number starting with 01 for the first version released in a
	// calendar year, then increasing for each version in that year.
	DatabaseVersion string `xml:"database_version"`


	// The date the file was created in international format (YYYY-MM-DD).
	DateOfCreation string `xml:"date_of_creation"`
}

Note I used the DatabaseVersion instead of the DateOfCreation as it reflects the last time the content was actually updated.

[Kuuuube]

Sounds good, thanks for the clarification.