feat: add the ability to add classes to tags

[holema]

… for h1-h5 an p. The classes which should be added the the paragraphes should be an array in the constructor.

[holema]

hello @Alex-D are you going to merge the request in the next version? if not, I have to use my version in my project, which is not my prefered way ;)

[holema]

Please review the fix I did

[Alex-D]

The added code is too big and can be simplified, or I miss something?
Feel free to tell me if I'm wrong.

[holema]

fixed it

[holema]

Hello Alex, will you merge this branch in the future?

[Alex-D]

I hope to merge it for the 2.22.0 soon, I just need to take some time to test it, and maybe rewrite it a bit :)

[Alex-D]

After re-read, I did not understand the value of a systematic addition of a class on an element. I let you add this on your own version, but I will not include it, sorry.

Thank you for your time :)

[holema]

The possibility is, that when you use bootstrap for examle, you need to add "h1-responsive" class to the h1 tag, to show it properly on all devices.
Also it is possible to add some sytling classes to the tags, e.Ex. I use special classes on blockquotes and set a z-depth to show drop shadows.