Soft-couple Language package to Filter package

This makes the Language package dependency for the Filter package
optional as it is is only required when `OutputFilter::stringURLSafe`
is used by the application.
Add joomla/language to require-dev
Merge pull request #188 from eddieajau/Filter

Soft-couple Language package to Filter package
Added missing sub-splits

Added the Linkedin and Router packages to the sub-split.
Merge pull request #190 from eddieajau/Build

Added missing sub-splits