Ftw-workspace

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- Use navtree properties to sort items on workspace overview.
[tschanzt]

- Fix broken upgradestep 1707 if no workspaces exists.
[elioschmutz]

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- Added new helper method to get icon or sprite for document tab.
[Julian Infanger]

- Show all users with local roles on a Workspace.
[mathias.leimgruber]

- Hide upload option of text field on Workspace and TabbedViewFolder.
[mathias.leimgruber]

- Fix misplaced checkbox in documents tab. Reset table configuration.
[elioschmutz]

- Use ftw.builder ImageBuilder, remove the ImageBuilder of this package.
[mathias.leimgruber]

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- Quick upload factory: also reindex dexterity types.
[jone]

- Add functionality for deleting and moving multiple documents
directly from the documents tab of the workspace.
[lknoepfel, elioschmutz]

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- Remove old, no longer used calendar js code.
[buchi]

- Update German, French and English translations.
[jone]

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- Fix quick_upload id generator (allow filenames staring with an '_')
[mathias.leimgruber]

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- Add txt preview adapter (shows just a txt.png).
[mathias.leimgruber]

- Add zip preview adapter (shows just a zip.png).
[mathias.leimgruber]

- Add pdf preview adapter (shows just a pdf.png).
[mathias.leimgruber]

- Add xlsx preview adapter (shows just a xlsx.png).
[mathias.leimgruber]

- Add xls preview adapter (shows just a xls.png).
[mathias.leimgruber]

- Add pptx preview adapter (shows just a pptx.png).
[mathias.leimgruber]

- Add ppt preview adapter (shows just a ppt.png).
[mathias.leimgruber]

- Add docx preview adapter (shows just a docx.png).
[mathias.leimgruber]

- Add doc preview adapter (shows just a doc.png).
[mathias.leimgruber]

- Add new fallback image for previews.
[mathias.leimgruber]