Add toggle for log vs. linear axes

[brittsikora]

Auto-scaling was throwing people off, so add ability to set limits. Or toggle between log axis and linear.

[jwildfire]

Might be handled by #9.

[samussiah]

I like @brittsikora 's second solution. Perhaps we could add a control to flip the axis scale. #9 involves maintaining a consistent axis whilst filtering. #15 will take care of that once #18 is merged in.

[jwildfire]

I'd say adding a log/linear toggle is nice to have, but I'm thinking it might be a little bit complex for this one ... or maybe not ... At any rate, I'm updating the title here to reflect that goal and bumping this to 1.3.