Add a simple demo

example/simple_demo.jl

@@ -0,0 +1,27 @@
+# A simple demo that can be run without jupyter notebooks.
+# First, activate the project (preferably after loading Revise), then include this file:
+# > using Revise
+# ] activate .
+# > include("example/simple_demo.jl")
+using SOLPS2IMAS: SOLPS2IMAS
+using GGDUtils: GGDUtils
+using Plots
+using SD4SOLPS
+
+sample_path = "$(@__DIR__)/../sample/ITER_Lore_2296_00000/"
+solps2imas_samples = splitdir(pathof(SOLPS2IMAS))[1] * "/../samples"
+
+dd = SD4SOLPS.preparation(
+    "Baseline2008-li0.70.x4.mod3.eqdsk",
+    [sample_path, solps2imas_samples]...;
+)
+
+grid_ggd = ids.edge_profiles.grid_ggd[1] # First grid_ggd time slice. It is allowed to vary in time
+space = grid_ggd.space[1] # First space in this grid_ggd
+
+# Choose backend
+gr()           # Fast and can save pdf
+# plotlyjs()   # Use for interactive plot, can only save png
+n_e = GGDUtils.get_prop_with_grid_subset_index(ids.edge_profiles.ggd[1].electrons.density, 5)
+plot(ids.edge_profiles.grid_ggd, n_e, colorbar_title="Electrons density / m^(-3)")
+plot!(space, GGDUtils.get_grid_subset_with_index(grid_ggd, 16), linecolor=:black, linewidth=2, linestyle=:solid, label="Separatix", legend=true)