[BUG] Offcenter Markers

[rsh52]

Markers appear to be slightly offcenter (slightly too far down) after the recent changes in #58

Notice how the red "X" and red circle in subject 2 are slightly off from each other.

Note: This is also the default behavior when using geom_text() and is probably related to complex calculations. This may not be worthwhile to fix, and should instead be left up to the user.

ggplot(data = all_events, mapping = aes(x = time_from_initial_infusion, y = pt_id, label = glyph)) + geom_text(size = 10)