Remove two Icelandic variants that are unfit for typing Icelandic.

The 'Sundeadkeys' and 'nodeadkeys' variants in the symbols/is file overwrite several keys of the standard Icelandic layout as if wanting to make them into German layouts. But in doing so they make essential punctuation and letters like hyphen (-) and question mark (?) and eth (ð) untypable, relegate ae (æ) to the third level, assign two keys to the same symbol (ö), and assign two keys to symbols that Icelandic doesn't use (ä and ü). Nobody can be using these variants to type Icelandic, and probably not any other language either because the essential question mark and hyphen are missing. So... these two patches simply remove the two variants.