Added "-e" flag test for volume maps reference

git-svn-id: https://svn.osgeo.org/grass/grass/trunk@46785 15284696-431f-4ddb-bdfa-cd5b030d7da7

raster/r.colors/test_volume_double_example1_hist.ref

@@ -0,0 +1,23 @@
+4 0:230:0
+5.02 0:226:0
+6.02 0:221:0
+7.02 0:212:0
+8.02 0:199:0
+9.02 0:182:0
+10.02 0:160:0
+11.02 23:146:0
+12.02 51:130:0
+13.02 83:116:14
+14.02 116:102:28
+15.02 120:112:34
+16.02 120:124:38
+17.02 132:137:42
+18.02 153:150:46
+19.02 172:162:52
+20.02 206:200:92
+21.02 230:227:121
+22.02 245:244:138
+23.02 252:252:147
+24 252:252:147
+nv 255:255:255
+default 255:255:255