Use more fine-grained texture specification for Pluto and Charon

data/scene/newhorizons.scene

 UseAccurateNewHorizonsKernels = false
-UseHighResolutionTextures = false
+-- TextureResolution = "low"
+TextureResolution = "med"
+-- TextureResolution = "high"
 
 function preInitialization()
     --[[

data/scene/newhorizons/pluto/charon/charon.mod

@@ -8,11 +8,12 @@ else
     }
 end
 
-if UseHighResolutionTextures then
-    ColorTexture = "textures/cpmap_cyl_HR_0e.jpg"
-else
-    ColorTexture = "textures/charon_highres.jpg"
-end
+Files = {
+    low = "textures/charon_highres.jpg",
+    med = "textures/charon_highres.jpg",
+    high = "textures/cpmap_cyl_HR_0e.jpg"
+}
+ColorTexture = Files[TextureResolution]
 
 return {
     -- CharonProjection module

data/scene/newhorizons/pluto/pluto/pluto.mod

@@ -9,11 +9,12 @@ else
     }
 end
 
-if UseHighResolutionTextures then
-    ColorTexture = "textures/pmap_cyl_HR_LOR_lowres.jpg"
-else
-    ColorTexture = "textures/Shenk_180.jpg"
-end
+Files = {
+    low = "textures/pluto_large.jpg",
+    med = "textures/Shenk_180.jpg",
+    high = "textures/pmap_cyl_HR_LOR_lowres.jpg"
+}
+ColorTexture = Files[TextureResolution]
 
 return {
     -- Pluto barycenter module
@@ -49,7 +50,7 @@ return {
                 Sequencing = "true"
             },
             Projection = {
-                Sequence       = "${OPENSPACE_DATA}/scene/newhorizons/pluto/pluto/images",
+                Sequence       = "${OPENSPACE_DATA}/scene/newhorizons/pluto/pluto/full_images",
                 EventFile      = "${OPENSPACE_DATA}/scene/newhorizons/pluto/pluto/assets/core_v9h_obs_getmets_v8_time_fix_nofrcd_mld.txt",
                 SequenceType   = "hybrid",
                 Observer       = "NEW HORIZONS",