plot_x_section: Plot a vertical cross section of a three dimensional field
In andrew-MET/mepsr: Utilities for MEPS data

Plot a vertical cross section of a three dimensional field

plot_x_section(.fcst_3d, point1, point2, surface_pressure,
  .proj4_string = "+proj=longlat +ellps=WGS84 +datum=WGS84 +no_defs",
  topo_color = "grey30", topo_highlight = "grey70", legend = TRUE,
  pressure_res = 10, horizontal_res = 1, ...)

`.fcst_3d`	A three dimseninal mepsr type object. Must have z as a named list element containng the level numbers.
`point1`	A vector of length 2 with the (x, y) location of the first point in the cross section. x and y will normally be longitude and latitude repsectively in decimal degrees. If x and y are in projected co-ordinates the proj4 string must be supplied in the `.proj4_string` argument.
`point2`	A vector of length 2 with the (x, y) location of the second point in the cross section. x and y must be in the same projection as `point1`.
`surface_pressure`	A two dimensional mepsr type object with the surface pressure in Pa on the same domain as `.fcst_3d`.
`.proj4_string`	The proj4 string for the cross section end points.
`topo_color`	The colour to shade the topogrpahy.
`topo_highlight`	The colour to highlight the top of the topography.
`legend`	Whether to plot a legend (TRUE / FALSE)
`pressure_res`	Vertical resolution of pressure levels in cross section (hPa).
`horizontal_res`	Horizontal resolution of cross section (km)
`...`	Arguments to image and image.plot.