GitLab

Restored OctreeCutcell example;
Added FixEdgeOrder, CheckEdgeOrder algorithms to check of consistency of
2d elements;
Element::Connect now uses FixEdgeOrder for faces;
Automatic grid dimension detection for vtk;
Fixed bug that sets may contain invalid links to elements even after
ApplyModification;
Corrected condition estimator in ddpqiluc;
Switched off pseudoinverse in bicgstab(l) since svd algorithm is bad.

Pseudoinverse for polynomial matrix in bicgstab(l) to improve stability
(as in petsc);
Added RowMerger class for sum of sparse rows.

Synchronizing various changes

Replaced russian comments in doxygen.
Examples with OpenGL would not lead to error in cmake if no library is
found.

Petsc understands common parameters. Support for different option files
for Petsc and Trilinos. Please see files in examples/MatSolve.

Install instructions from readme file were tested on Linux machine.

Added code comments, small fixes and improvements.