deltaT().value() to deltaTValue()
and
    deltaT0().value() to deltaT0Value()
across the whole code - faster to return especially if being used
often, in each call to a submodel for example.

and other unit conversion functions as they are required e.g. slug <-> kg.

by providing the independent objects directly.

Devirtualised functions which should not be overridden and so than some functions can be inlined for efficiency.

http://www.cfd-online.com/Forums/openfoam-bugs/69141-compilation-order-single-precision-issues.html

- note left utilities/mesh/advanced/collapseEdges/collapseEdges.C as-is.
  It looks suspicious, but the change was recent, so maybe it means something

- removed/renamed one level of directories, not all constants are dimensioned
    global/dimensionedConstants -> global/constants/
    global/dimensionedConstants/constants/* -> global/constants/

- formatting and doxygen cleanup

- added degToRad() and radToDeg() inline functions (in mathematicalConstants)
  removed equivalent degToRad() from engineTime