ggplot: Beautify Labels in Facets

Fixing particular cases when faceting:
- Space and alignment for plots using facet_wrap(). https://plot.ly/~pdespouy/491 vs https://plot.ly/~pdespouy/595
- Clean "new text" annotations. https://plot.ly/~pdespouy/490 vs https://plot.ly/~pdespouy/594
- Angles on yaxis label. https://plot.ly/~pdespouy/491 vs https://plot.ly/~pdespouy/678
- Alignment and spacing on the yaxis, using facet_grid(). https://plot.ly/~pdespouy/641 vs https://plot.ly/~pdespouy/795

Spacing around operators is not very consistent here.
Multiplication has priority over addition and subtraction, so spacing around `*` should be less or equal to spacing around `-` and `+`.