Simplified the client-side API a bit, with the decision that uploading is always additive.
Extended the functionality to allow setting the default text as well.
Added another ligature for the cancel-icon, to allow it to double as close.

- Also added the icomoon project-json for more easily adding future icons.
Updated the PromptForLanguage to use some generic popup-components to better prepare for more popups in the future.
Updated the PromptForLanguage popup to support the new features of the file-upload file.

- Added translations for the popup.
Removed old reference to the delete-unused checkbox.
Added a button for deleting tables.
Updated the language file with some missing texts.
Updated the uploading to fix some minor issues here and there.

- Updated the upload-popup with a close-button.
- Translated all missing texts.
- Added a checkbox for setting uploaded files as default text.