v1.0.3: ssdtools 1.0.3

- Replaced `size = 0.5` with `linewidth = 0.5` in `geom_hcintersect()` and `geom_xribbon()`.
- Replaced `aes_string()` with `aes()` in examples (and internally).
- Removed use of `tidyverse` package.
- Now tests values to 12 significant digits.
- Fixed description of `ssd_hp()` to be percent affected rather than percent protected.