Prepared the 4.9.0 release

easybook 4.8.0 version

version 4.6.0

fixed #26 - Make Slugger work when `iconv()` function is unavailable

Fixed package name in composer.json

The package name must have a vendor name, a forward slash, and a package name, matching [a-z0-9_.-]+/[a-z0-9_.-]+.