StudioLight: Add new centered studiolight setup

This is to have one studiolight that is symetrical and close to
the basic_1 matcap.

release/datafiles/studiolights/studio/basic.sl

@@ -0,0 +1,48 @@
+version 1
+light_ambient.x 0.000000
+light_ambient.y 0.000000
+light_ambient.z 0.000000
+light[0].flag 1
+light[0].smooth 0.100000
+light[0].col.x 0.507074
+light[0].col.y 0.507074
+light[0].col.z 0.507074
+light[0].spec.x 0.666141
+light[0].spec.y 0.666141
+light[0].spec.z 0.666141
+light[0].vec.x 0.000000
+light[0].vec.y 0.639175
+light[0].vec.z 0.769061
+light[1].flag 1
+light[1].smooth 0.340000
+light[1].col.x 0.021936
+light[1].col.y 0.058160
+light[1].col.z 0.063719
+light[1].spec.x 0.033668
+light[1].spec.y 0.060061
+light[1].spec.z 0.063712
+light[1].vec.x -0.846939
+light[1].vec.y -0.357143
+light[1].vec.z 0.393883
+light[2].flag 1
+light[2].smooth 0.340000
+light[2].col.x 0.063721
+light[2].col.y 0.040061
+light[2].col.z 0.037017
+light[2].spec.x 0.069396
+light[2].spec.y 0.046455
+light[2].spec.z 0.046455
+light[2].vec.x 0.755102
+light[2].vec.y -0.530612
+light[2].vec.z 0.385060
+light[3].flag 1
+light[3].smooth 0.724138
+light[3].col.x 0.000000
+light[3].col.y 0.000000
+light[3].col.z 0.000000
+light[3].spec.x 0.023079
+light[3].spec.y 0.023393
+light[3].spec.z 0.025394
+light[3].vec.x 0.034483
+light[3].vec.y 0.913793
+light[3].vec.z 0.404714