add mention of ggThemeAssist in the plotting lesson?

[fmichonneau]

See: https://github.com/calligross/ggthemeassist

[aurielfournier]

My initial reaction to this is very mixed but this does seem to help bridge the difficulties of all the different theme arguments. I'm just not a big GUI fan, but it would help.

[Pakillo]

Perhaps it can be mentioned at the end ('More resources' links), together with ggedit.

I'm no big fan of these GUIs either, but in my (short) experience new users get very intimidated to modify themes based on ?theme (shocked by element_text, element_rect, etc). And seeing that they can change appearance much easier interactively, helps a lot. And you get back the code that implements those changes, so not that bad...

I vote for linking to both packages in the end, and perhaps mentioning them in one sentence in the main text.

[anacost]

Both have been added to the tidyverse-first branch (ggThemeAssist and ggedit). (#400)