- change error-handling to exceptions

[[Imported from SVN: r1827]]

[[Imported from SVN: r1826]]

list the head point is obsolete. Removed it.

[[Imported from SVN: r1825]]

[[Imported from SVN: r1824]]

[[Imported from SVN: r1823]]

[[Imported from SVN: r1822]]

[[Imported from SVN: r1821]]

[[Imported from SVN: r1820]]

[[Imported from SVN: r1819]]

[[Imported from SVN: r1818]]

from information obtained from neighbouring processes.

[[Imported from SVN: r1817]]

[[Imported from SVN: r1816]]

[[Imported from SVN: r1815]]

[[Imported from SVN: r1814]]

[[Imported from SVN: r1813]]

[[Imported from SVN: r1812]]

  markAsDeleted method has O(log(N)) complexity because of the binary
  search.

- Removed bug when deleting indices. The deleted  index pairs were not
  removed when no indices where added.

- added possibility to print the index sets for debugging.

[[Imported from SVN: r1811]]

only partially implemented for simplex, but it should not disturb
other code.

[[Imported from SVN: r1810]]

[[Imported from SVN: r1809]]

[[Imported from SVN: r1808]]

sample code.

[[Imported from SVN: r1807]]

[[Imported from SVN: r1806]]

This seems to be natural as there also is the possibility to get an
iterator positioned before the first element.

[[Imported from SVN: r1805]]

[[Imported from SVN: r1804]]

[[Imported from SVN: r1803]]

[[Imported from SVN: r1802]]

[[Imported from SVN: r1801]]

* cleaned out equals and dereference

[[Imported from SVN: r1800]]

[[Imported from SVN: r1799]]

[[Imported from SVN: r1798]]

[[Imported from SVN: r1797]]

[[Imported from SVN: r1796]]

* new GridTraits
* removed equals and dereference from the Iterator classes

[[Imported from SVN: r1795]]

[[Imported from SVN: r1794]]

[[Imported from SVN: r1793]]

[[Imported from SVN: r1792]]

[[Imported from SVN: r1791]]

[[Imported from SVN: r1790]]

[[Imported from SVN: r1789]]

Not seriously tested yet, though.

[[Imported from SVN: r1788]]