Add docs/README.txt
Add Sphinx docs
Add to .gitignore
Add sphinx13 theme
Move images to new docs folder
update sphinx docs layout
delete html documentation
Move latex documentation to docs
update sphinx docs
Use "true" argument in calls to cholesky methods.
Improve Doxygen documentation, add at() methods and value assignment operator.
Remove const at() methods (swig does not recognized them)
Correct invert() method.

The invert() method does not need to call the Cholesky decomposition, as cholseky_invert() does this itself.
Add missing line continuation marker.
Improve Doxygen documentation, add at() method and value assignment method.
Adapt to new matrix interface.
Use at() method for argument range checking test.

The [] access operator does not provide range checking anymore, hence the at() method has not to be used for range checking.
Add value assignment operator check.
Expose GTools functions to Python.
Replace operator* by __mul__ operators.