DynamicList changes.

- setSize() adjusts the addressable length only.
  Changed setSize(label) usage to setCapacity(label) or reserve(label)
  throughout. The final name (capacity vs. storageSize() vs. whatever) can
  easily be decided at a later date.
- added setSize(label, const T&), which may still not be really useful, but
  is at least now meaningful
- made shrink() a bit more legible.
- added append(UList<T>&)
- copying from a UList avoids reallocations where possible

The following bits of code continue to use the DynamicList::setSize(), but
appear to be legitimate (or the corresponding code itself needs rethinking).

  src/OpenFOAM/meshes/primitiveMesh/primitiveMeshPointCells.C:167: error: within this context
  src/OpenFOAM/lnInclude/faceTemplates.C:44: error: within this context
  src/surfMesh/surfaceFormats/tri/TRIsurfaceFormatCore.C:178: error: within this context
  src/dynamicMesh/polyTopoChange/polyTopoChange/polyTopoChange.C:737: error: within this context
  src/dynamicMesh/polyTopoChange/polyTopoChange/polyTopoChange.C:741: error: within this context
  src/dynamicMesh/polyTopoChange/polyTopoChange/polyTopoChange.C:745: error: within this context
  src/dynamicMesh/polyTopoChange/polyTopoChange/polyTopoChange.C:749: error: within this context
  src/dynamicMesh/polyTopoChange/polyTopoChange/polyTopoChange.C:754: error: within this context
  src/dynamicMesh/polyTopoChange/polyTopoChange/polyTopoChange.C:935: error: within this context
  src/dynamicMesh/polyTopoChange/polyTopoChange/polyTopoChange.C:940: error: within this context
  src/dynamicMesh/polyTopoChange/polyTopoChange/polyTopoChange.C:1041: error: within this context
  src/dynamicMesh/polyTopoChange/polyTopoChange/polyTopoChange.C:1046: error: within this context
  src/dynamicMesh/polyTopoChange/polyTopoChange/polyTopoChange.C:2161: error: within this context
  src/dynamicMesh/polyTopoChange/polyTopoChange/polyTopoChange.C:2162: error: within this context
  src/dynamicMesh/polyTopoChange/polyTopoChange/polyTopoChange.C:2201: error: within this context
  src/dynamicMesh/polyTopoChange/polyTopoChange/polyTopoChange.C:2205: error: within this context
  src/dynamicMesh/polyTopoChange/polyTopoChange/polyTopoChange.C:2261: error: within this context
  src/dynamicMesh/polyTopoChange/polyTopoChange/polyTopoChange.C:2262: error: within this context
  src/dynamicMesh/polyTopoChange/polyTopoChange/polyTopoChange.C:2263: error: within this context
  src/dynamicMesh/polyTopoChange/polyTopoChange/polyTopoChange.C:2264: error: within this context
  src/dynamicMesh/polyTopoChange/polyTopoChange/polyTopoChange.C:2265: error: within this context
  src/dynamicMesh/polyTopoChange/polyTopoChange/polyTopoChange.C:3011: error: within this context
  src/dynamicMesh/polyTopoChange/polyTopoChange/polyTopoChange.C:3076: error: within this context
  src/dynamicMesh/polyTopoChange/polyTopoChange/polyTopoChange.C:3244: error: within this context
  src/dynamicMesh/polyTopoChange/polyTopoChange/polyTopoChange.C:3371: error: within this context
  src/dynamicMesh/meshCut/cellLooper/topoCellLooper.C:73: error: within this context
  src/dynamicMesh/meshCut/cellLooper/topoCellLooper.C:91: error: within this context
  src/dynamicMesh/meshCut/cellLooper/topoCellLooper.C:73: error: within this context
  src/dynamicMesh/meshCut/cellLooper/topoCellLooper.C:91: error: within this context