Wanted: add res and function option for SObin

[Maschette]

currently SObin gives you the option for dimensions of the raster it bins into, these aren't always the easiest to know what they should be in some data sets and it would be easier to give a cell resolution (eg res=c(0.25,0.125)) and have SObin calculate the dimensions needed to get that cell size.

Similarly SObin uses n() within dplyr summarize by default, it would be great to add the options for mean, median, min and max.

i can probably do the latter ineloquently but I'm not sure about the res one, @mdsumner?

[raymondben]

res parameter added in d6b0217
@Maschette how do you want the function option to work, in terms of providing the data values? Binning to a density raster (as it does now) only requires the x, y locations. To apply a mean or other function we'd also need to add a z parameter that gives the data value at each location. Is that what you were envisaging?

[mdsumner]

ask me about using the warper and the datapointer thing for GDAL for regridding to min, max, sum, or mean with a target_res - in a few weeks maybe, it's all a bit flaky atm