Benchmark gravitation

See 0dbc299fdc4 for the cost of templatisation (between 15% and 20%).
Both before and after, the difference between native and CLR is about 10%.
[Nope.](http://google-styleguide.googlecode.com/svn/trunk/cppguide.xml?showone=Function_Declarations_and_Definitions#Function_Declarations_and_Definitions)
>Some points to note:
> * If you cannot fit the return type and the function name on a single line, break between them.
> * If you break after the return type of a function definition, do not indent.