docs(ridfire)

Added more documentation, also moved all engine code into
gridfire::engine namespace to be more in line with other parts of teh
code base

src/include/gridfire/solver/strategies/strategies.h

@@ -0,0 +1,5 @@
+#pragma once
+
+#include "gridfire/solver/strategies/triggers/triggers.h"
+#include "gridfire/solver/strategies/strategy_abstract.h"
+#include "gridfire/solver/strategies/CVODE_solver_strategy.h"