overlap/overwrite axis calls

[lindsayplatt]

gs <- gsplot() %>% 
    points(0:1,0:1) %>% 
    axis(side=1, at=c(0.5,1)) %>% 
    axis(side=1, at=c(0.25, 0.75))
gs

Should plot have 0.25, 0.5, 0.75, and 1 ticks to match base behavior?

Suggestion:

gs <- gsplot() %>% 
    points(0:1,0:1) %>% 
    axis(side=1, at=c(0.5,1)) %>% 
    axis(side=1, at=c(0.25, 0.75), append=TRUE)
gs

• always assume axis call exists (default) for append/replace
  to not draw axis lines: use lwd=0 and lwd.ticks=1 ??

[lindsayplatt]

closed by #410