Add ligatures support

[nicolabricot]

Hi Andreas

Thanks for the great font! I've used it for French documents, it's awesome 👍.
Will you add later ligatures support?

Have a nice day 😃

[larsenwork]

Which ligatures? There should be a bunch of them already. Look in the readme pdf 😄

[jbcpollak]

@larsenwork - Is Gidole still supported?

We would be interested in the dutch ij ligature - https://en.wikipedia.org/wiki/IJ_(digraph)