'set -x' should be used for debugging.

Added command printing into wmake and Allwmake as a replacement for
'set -x' to log current target.

Resolves bug-report http://bugs.openfoam.org/view.php?id=2194

Patch contributed by Bruno Santos
Resolves bug-report http://bugs.openfoam.org/view.php?id=2193

Resolves bug-report http://www.openfoam.org/mantisbt/view.php?id=2053

Patch contributed by Bruno Santos

Patch contributed by Bruno Santos
Resolves bug-report http://www.openfoam.org/mantisbt/view.php?id=2032

Contributed by Bruno Santos
Resolves patch report http://www.openfoam.org/mantisbt/view.php?id=2023

Update online documentation http://openfoam.github.io/Documentation-dev/html/

Avoids the clutter and maintenance effort associated with providing the
function signature string.

Patch provided by Bruno Santos
Resolves bug-report http://www.openfoam.org/mantisbt/view.php?id=1528

and generate cleaner HTML files.
Thanks to Bruno Santos for various fixes and improvements.
Resolves bug reports:
    http://www.openfoam.org/mantisbt/view.php?id=1516
    http://www.openfoam.org/mantisbt/view.php?id=1016
    http://www.openfoam.org/mantisbt/view.php?id=1512