Axis stuff

[coveralls]

Coverage increased (+0.2%) to 80.517% when pulling 102876ae3f49d011df68f8e52a88f1a7b5608fb2 on ldecicco-USGS:axis_stuff into f3fdd8b525eb9a373d6335fdd3af529d87244a26 on USGS-R:master.

[lindsayplatt]

Fixing #453. The following examples work with this PR:

# this should give a warning - you can't use "log" inside an axis call
gsplot() %>%
     points(1:100, 1:100, log="xy", side=c(3,4)) %>%
     axis(side=c(1), log="") 
Warning message:
In axis(side = side, at = at, labels = labels, ...) :
  "log" is not a graphical parameter

# this is how you would have side 3 and 4 logged, but not 1
gsplot() %>%
    points(1:100, 1:100, log="xy", side=c(3,4)) %>%
    view(side=c(1,2), log='') %>% 
    axis(side=1) 

# this should log sides 3 & 4, but not 1 & 2
gsplot() %>%
    points(1:100, 1:100, log="xy", side=c(3,4)) %>%
    points(1:10,1:10, log="", side=c(1,2))

This is somewhat a continuation of #414.

# this has sides 1,2 not logged and side 4 logged (no side 3)
gs <- gsplot() %>% 
    points(1:2,c(2,25)) %>% 
    points(c(1,2), c(1, 1000000000), side=4, log='y') 
gs