Rename text resources consistently

- keylabel_<key>, the key label text of the <key>
- keyspec_<key>, the key specification of the <key>
- keyhintlabel_<key>, the hint label text of the <key>
- morekeys_<key>, the more keys specifications of the <key>
- additional_morekeys_<key>, the additional more keys specification of
  the <key>

Change-Id: Ib2127f21fa33a2568e8a6eba65cfdb2cf78b480e