Added german translations

[Mr-Kanister]

Based on some of your commits I added some missing german translations. Is it somehow possible to get an overview of what's still missing?

[personalizedrefrigerator]

Everything missing a German translation in version 0.21.0:

image: Image

reformatSelection: Format selection

inputAltText: Alt text:

chooseFile: Choose file:

submit: Submit

cancel: Cancel

textSize: Size:

documentProperties: Page

backgroundColor: Background Color:

imageWidthOption: Width:

imageHeightOption: Height:

useGridOption: Grid:

toggleOverflow: More

pressureSensitiveFreehandPen: Freehand (pressure sensitive)

lockRotation: Lock rotation

paste: Paste

imageSize: (t,e)=>`Image size: ${t} ${e}`

errorImageHasZeroSize: Error: Image has zero size

imageLoadError: t=>`Error loading image: ${t}`

selectAllTool: Select all shortcut

textTool: Text

changeTool: Change tool

pasteHandler: Copy paste handler

soundExplorer: Sound-based image exploration

disableAccessibilityExploreTool: Disable sound-based exploration

enableAccessibilityExploreTool: Enable sound-based exploration

findLabel: Find

toNextMatch: Next

closeFindDialog: Close

findDialogShown: Find dialog shown

findDialogHidden: Find dialog hidden

focusedFoundText: (t,e)=>`Viewing match ${t} of ${e}`

copied: (t,e)=>`Copied ${t} ${e}`

pasted: (t,e)=>`Pasted ${t} ${e}`

unionOf: (t,e)=>`Union: ${e} ${t}`

unlabeledImageNode: Unlabeled image

emptyBackground: Empty background

filledBackgroundWithColor: t=>`Filled background (${t})`

imageNode: t=>`Image: ${t}`

restyledElement: t=>`Restyled ${t}`

imageNodeCount: t=>`There are ${t} visible image nodes.`

Thank you for your work!

[Mr-Kanister]

I hope everything's complete and fairly well translated now ;)

[personalizedrefrigerator]

This looks good to me! Thank you!!