Started working on adding additional layouting algorithms, see #59

- Added JungLayouting library and used implemented automatic layouting in a few ways, using available algorithms
- Added Layouting menu where users can choose one of the available layouting algorithms and activate it.
Added box layout algorithm, corrected some small mistakes, see #59
Corrected the problem of saving the imported KROKI project to the same
file from which it was imported. Corrected an error in import noticed
when trying to start the imported KROKI diagram as a desktop
application.
Changed the code that determines the state of the canvas that shows the
Standard form, because it did not always set the Resize state when the
cursor was on the handles for resizing a Standard form.
Changed the predefined height of the canvas that shows the Standard
form.
Saving and loading changed

Optimized saving and loading from xml files. As it is still problematic to load very large xml files, added saving and loading as GZip streams, as a temporary solution.
Merge branch 'master' of https://github.com/KROKIteam/KROKI-mockup-tool
When saving for the first time also use gzip to save KROKI diagram.
Creating and deleting shortcuts bug fix

- Creating only one shortcut to a given element inside one diagra
- Cutting shortcuts now works even if it is not in the same diagram as the element it points to
Fixed a small bug which occured while cutting shortcuts when both elements are shortcuts
Opening diagrams by clicking on tree nodes fixed
Removed tree layouter
Saving class diagrams in the same file as the rest of the project

- Diagrams are not being saved separately anymore
- Saving diagrams to the same file as the rest of the project, using gzip
- Layouting is performed even if the diagram was loaded, but was not open before (inside packages)
Small layouting bug fix
Fixed a problem where the names of the associations weren't properly shown in all cases
Added Administration Subsytem and connected with KROKI-MockupTool.
Merge branch 'master' of https://github.com/KROKIteam/KROKI-mockup-tool
Excluded libraries
Added initiral data when new administration subsytem is created.
For import added the option for user to enter text that he wants to
remove as a prefix or suffix from the names of the package, class,
property or operation elements that are being imported.
Made so that the components on the standard form are aligned to the
left.
Added remove option for texts to be removed during import of UML
diagram.
Merge branch 'master' of https://github.com/KROKIteam/KROKI-mockup-tool