allow switch/bool values for writeCompression in system/controlDict

- eg,
    writeCompression false; or writeCompression uncompressed;
    writeCompression true;  or writeCompression compressed;

improves consistency with other controlDict parameters

- compatibility:
  * 'polySpline' and 'simpleSpline' accepted
  * detect and discard end tangent specifications

- a BSpline is also included (eg, for future support of NURBS), but is
  not selectable from blockMesh since it really isn't as nice as the
  Catmull-Rom (ie, doesn't *exactly* go through each point).

triangle, from:

http://en.wikipedia.org/wiki/Inertia_tensor_of_triangle

Adding the ability to calculate the inertia tensor of a polygon face
by summing the triangle inertias.

Added a test application to draw a test face with its principal
axes and moments of inertia.

- also looks reasonable and doesn't deviate much from Catmull-Rom

- the current B-Splines deliver rubbish

- now that I re-examined the code, the note in commit 51fd6327
  can be mostly ignored

  PackedList isMaster(nPoints, 1u);
  is not really inefficient at all, since the '1u' is packed into
  32/64-bits before the subsequent assignment and doesn't involve
  shifts/masking for each index

  The same misinformation applies to the PackedList(size, 0u) form.
  It isn't much slower at all.

  Nonetheless, add bool specialization so that it is a simple assign.

- to match coding guidelines

- ensure that the standard options (eg, from timeSelector) also have
  some usage information

- bugfix: noParallel() didn't remove 'parallel' from validParOptions
  allowing it to sneak through to the Pstream layer.
  noParallel() now clears the entire validParOptions as well

- new convenience methods
  * addOption()
  * removeOption()
  * addBoolOption() - as per addOption(), but for bool options (no param)

- printUsage() output format
  * options sorted alphabetically
  * options listed on separate lines for better readability

- new optionUsage static member for short usage information about
  an option
  * corresponding addUsage() method or provide usage information
    in addOption() / addBoolOption()

Note:

PackedList constructor initializes to zero, faster not to do it
ourselves.
ie,
    PackedList foo(nPoints);
vs.
    PackedList foo(nPoints, 0);

saves an extra nPoints operations with shifts/masks etc.

If speed is important, change this type of code

    PackedList isMaster(nPoints, 1u);
    for (loop)
    {
        if (condition)
        {
            isMaster.set(i, 0u);   // unset bit
        }
    }
    return isMaster;

into this:

    PackedList notMaster(nPoints);
    for (loop)
    {
        if (!condition)
        {
            notMaster.set(i, 1u);
        }
    }
    notMaster.flip();
    return notMaster;

or this:

    PackedList isMaster(nPoints);
    isMaster.flip();

    for (loop)
    {
        if (condition)
        {
            isMaster.set(i, 0u);
        }
    }
    return isMaster;