Igk1972 improved tinymce parameters

[igk1972]

Add worked tinymce params:

• block_formats
• style_formats
• content_css
• invalid_elements (span tag fix)
• extended_valid_elements (span tag fix)

[newbthenewbd]

Please accept my sincere apologies for the delayed response - while working on resolving some of the issues reported for the plugin, I had simply forgotten about this pull request, which, as GitHub claimed, furthermore had a conflict. Turns out that the conflict was nothing serious, however I'll need a few things resolved before this gets merged, namely:

• Every TinyMCE parameter set that goes below the parameters loop (and as such, cannot be overridden by parameters in tinymce-editor.yaml) should be reflected in tinymce-editor.yaml, while parameters which do not pose an XSS risk should also be fully configurable from within the admin panel, thus I'd like to request that the appropriate blueprints and configuration entries are made. I may contribute the appropriate translations for languages.yaml once I fully understand what these parameters do.
• In relation to the above, I believe that the parameters invalid_elements, extended_valid_elements and invalid_styles may be redundant - invalid_styles does not seem to serve any purpose in this pull request (or does it?), while invalid_elements and extended_valid_elements could be configured by an individual user from within the admin plugin or through modifying tinymce-editor.yaml. Hence I'd like to request that You elaborate on what issues the span tag fix specifically solves, and if it's indeed of major benefit for the general TinyMCE usecases, I will request that the parameters are added to tinymce-editor.yaml, instead, because these parameters should by definition be extensible, unlike e.g. convert_urls, which could simply go above the parameters loop as a default value.
• Last but not least, I'd like to request that the pull request is submitted to the develop branch, as master is meant for complete releases, even though their commits are usually on par... Maybe I should finally get myself to write a CONTRIBUTING.md to avoid creating such inconveniences in the future. 🙃

Thanks!

[newbthenewbd]

Actually, one more thing that should probably be made clear - because content_css is not extensible, i.e. the user modifying it won't actually be willing to modify something completely different, but specifically the CSS, its inclusion in tinymce.html.twig is permissible, but please move it above the parameters loop, preferably right above plugins.

Thanks!