This is faster than the library functionality that it replaces, as it
allows the compiler to do inlining. It also does not utilise any static
state so generators do not interfere with each other. It is also faster
than the the array lookup in cachedRandom. The cachedRandom class
therefore offers no advantage over Random and has been removed.
For compatibility with all the mesh and related classes in OpenFOAM The 'normal'
function of the 'triangle', 'triFace' and 'face' classes now returns the unit
normal vector rather than the vector area which is now provided by the 'area'
function.
Updated the tetrahedron and triangle classes to use the barycentric
primitives. Removed duplicate code for generating random positions in
tets and tris, and fixed bug in tri random position.
