Merge pull request #72 from JeanFrancoisViaud/master

Lattice tutorial
Correct cide.bib
Merge pull request #73 from chdemko/master

Correct cide.bib
Use jacoco 0.7.0
Merge pull request #74 from chdemko/master

Use jacoco 0.7.0
Remove test of instance
Merge pull request #75 from chdemko/master

Remove test of instance
Change comments
Merge pull request #76 from chdemko/master

Change comments
Don't catch IOException
Merge pull request #77 from chdemko/master

Don't catch IOException
Remove constructor by copy for Node
Merge pull request #78 from chdemko/master

Remove constructor by copy for Node
Update examples
Merge pull request #79 from chdemko/master

Update examples
Implement abstract writer pattern for DGraph
Correct tutorial
Correct tutorial
Register default writer only if it has not been set
Merge pull request #80 from chdemko/master

Implement abstract writer pattern for DGraph