Simplify RadialSolution

Author: robertodr

CHANGELOG.md

@@ -13,6 +13,9 @@
 
 - The versioning machinery has been updated. The update was inspired by the
   `versioner.py` tool devised by @loriab.
+- The implementation of the `RadialSolution` for the second order ODE
+  associated with the spherical diffuse Green's function is less heavily
+  `template`-d.
 
 ## [Version 1.2.0-rc1] - 2018-03-02