plothist(x) now uses hist(x), fix ticks on x

```Histogram``` on Winston.jl set ```x0``` to 0 by default (have a fix me comment) and I don't know how to fix it.
For fix it on ```plothist()```, I subtract the ```start``` of the range to ticks (in order to start on 0), but I use the range for labels in order to get the desired output.
Works fine, except when the number of bins is too large (labels superpose between them, but can be fixed by user setting a ```nbins``` to a lower number for example).