hadley/ggplot2 — pull request #637 by wch (2012-08-02 21:29:57+00:00)
Title: Limit map gridline range. Fixes #562

This fixes #562. Examples that are fixed by this:

```R
skyplot2 <- qplot(RA,Dec,data=sky2,xlim=c(0,360),ylim=c(-89.999,89.999))

skyplot2 + coord_map(projection="aitoff",orientation=c(89.999,180,0)) +
scale_y_continuous(breaks=(-2:2)*30,limits=c(-89,89)) +
scale_x_continuous(breaks=(0:8)*45,limits=c(0,360), labels=c("","","","","","","","","")) +
theme(panel.grid.major = theme_line(colour='black'))

skyplot2 + coord_map(projection="lagrange",orientation=c(89.999,180,0)) +
scale_y_continuous(breaks=(-2:2)*30,limits=c(-89.999,89.999)) +
scale_x_continuous(breaks=(0:8)*45,limits=c(0,360), labels=c("","","","","","","","","")) +
theme(panel.grid.major = theme_line(colour='black'))
```