Draft: Add sphinx documentation

The mechanism for building docs was copied from EveryBeam; it parses both Doxygen documentation and python documentation into a sphinx page.

cpp/settings.h

@@ -18,7 +18,15 @@ namespace radler {
  * @brief The value of LocalRmsMethod describes if and how an RMS map
  * should be used.
  */
-enum class LocalRmsMethod { kNone, kRmsWindow, kRmsAndMinimumWindow };
+enum class LocalRmsMethod {
+  /// No local RMS
+  kNone,
+  /// Spatially varying RMS image
+  kRmsWindow,
+  /// Spatially varying RMS image with min. Computed as max(window RMS, 0.3 x
+  /// window min)
+  kRmsAndMinimumWindow
+};
 
 /**
  * @brief The deconvolution algorithm type.