Show "other" whitespaces in a unified whitespace-tag

For TRANSLATE-1249 we need to distinguish between whitespace tags and non-whitespace tags.

Therefore we need to extend TRANSLATE-1130 so that all whitespace characters listed in TRANSLATE-1249 are shown as whitespace tags. For simplicity those chars that currently are not associated with a special character display should get a unified tag symbol (please choose one) - one symbol, that symbolizes "other whitespaces".

For a list of whitespace characters, please see TRANSLATE-1249