I would like to create a theme that has tick marks different from the default, to avoid repeating `+ scale_x_continuous` every time I create a custom plot. 

Let's take a simple example, in which I want only tick marks at the limits:

```
A = 1; f = 5; p = 0; d = 0.4
t = seq(from = 0, to = 10, by = 0.01)

x = A * sin(t * f + p) * exp(-d * t)
numticks = 1

qplot(x = t, y = x) + theme_classic() + 
  scale_x_continuous(breaks = scales::trans_breaks("identity", function(x) x, n=numticks) )

```

This looks great (see below), but ideally I would be able to produce the same result without using `scale_x_continuous` as it's clunky. I want to replace `theme_classic()` with `+ mytheme` and that should solve it.

Here's my best attempt so far at a solution:

```
mytheme <- theme_classic() + 
theme(scale_x_continuous(breaks=trans_breaks("identity", function(x) x, n=numticks)) 

```

Not sure if this is even possible, and happy to keep typing `scale_x_continuous(...)` every time. But it would be even better to change the defaults temporarily or, even better, in a custom theme.

Here's the plot axes I want to produce btw, and I want to produce many such plots (for plotting [harmonographs](http://en.wikipedia.org/wiki/Harmonograph)):

![custom x axis](https://i.stack.imgur.com/7QTjl.png)