Refactor, separate docs from headers, add ru docs

Doxygen kind'a sucks and I need multilanguage documentation, so I did
that. Also, separated massive Math.h file into smaller files.

include/BH/Math/Plane.h

@@ -0,0 +1,24 @@
+#ifndef BH_MATH_PLANE_H
+#define BH_MATH_PLANE_H
+
+#include "../Common.h"
+
+
+int BH_PlaneFromPoints(const float a[3],
+                       const float b[3],
+                       const float c[3],
+                       float out[4]);
+
+
+
+float BH_PlaneDistance(const float plane[4],
+                       const float point[3]);
+
+
+
+void BH_PlaneClosestPoint(const float plane[4],
+                          const float point[3],
+                          float out[3]);
+
+
+#endif /* BH_MATH_PLANE_H */