UI/Python: rename Lamps to Lights, to follow more standard terminology.

Internally it's still mostly named lamps, though some modules like Cycles
were already calling them lights.

source/blender/makesrna/intern/rna_access.c

@@ -620,7 +620,7 @@ StructRNA *RNA_struct_base(StructRNA *type)
 /**
  * Use to find the subtype directly below a base-type.
  *
- * So if type were `RNA_SpotLamp`, `RNA_struct_base_of(type, &RNA_ID)` would return `&RNA_Lamp`.
+ * So if type were `RNA_SpotLIght`, `RNA_struct_base_of(type, &RNA_ID)` would return `&RNA_Light`.
  */
 const StructRNA *RNA_struct_base_child_of(const StructRNA *type, const StructRNA *parent_type)
 {