Improve the "Vanila Theme": font and display issues for compatibility with Pd-Vanilla

[porres]

this is a reboot of https://github.com/plugdata-team/plugdata/issues/1656

First I'd like to ask for

• [ ] A theme named 'vanilla' instead of classic

Now for some display and font issues. You see, a Vanilla theme would require the 'Menlo' font, and also the fact that setting the font in the settings should affect comments, objects and all text in a patch. We can set the 'Menlo' font alright, but it doesn't affect the patch. So we need to

• [ ] make the font theme set text in a patch (old discussion in https://github.com/plugdata-team/plugdata/issues/1691)

I would also like to discuss if we can't just use 'menlo' as the default font for plugdata to improve compatibility in general, not only for the vanilla theme... so

• [ ] make menlo the default font for plugdata (old discussion in https://github.com/plugdata-team/plugdata/issues/1692)

Another issue with font is iemguis, who should have a hardcoded font instead of loading the font from the theme, and it should really be those available in the original Vanilla distribution. If matching the font to the one PlugData uses is important, that's another reason to set 'menlo' as the default one.

• [ ] make labels from iemguis to have a hardcoded font (old discussion in https://github.com/plugdata-team/plugdata/issues/1671)

For last, plugdata doesn't recall the font size saved with the patch, but it should

• [ ] Make PlugData load font size according to the patch (old discussion in https://github.com/plugdata-team/plugdata/issues/1663)