cre text selection: grab word when just holding and not panning
cre text selection: grab word when just holding and not panning

This reverts the behaviour introduced by 01a39e9 (#742) when just
holding and not panning.
Otherwise, when holding to just do a dictionary lookup:
- when holding on a space or a punctuation, this char would be and
  stay highlighted while the dict lookup would not happen because
  text selection would have been cleaned and become empty.
- when holding on a blank space (eg: after the last word on a
  non-full last line), no text would be selected here, but
  getWordFromPosition(), used as a fallback, would return the
  nearest word on above or below line, which would then be used
  as dict lookup input, with a few side effects: no highlighting
  done while looking up; if then Highlighted from the dict window
  button and bookmarked, the bookmark would have no text and no
  highlight box would be shown when revisiting the page...
So, best to get back the still unperfect previous behaviour.

koreader/koreader-base,Frenzie/koreader-base,koreader/koreader-base,koreader/koreader-base,NiLuJe/koreader-base,Frenzie/koreader-base,houqp/koreader-base,NiLuJe/koreader-base,houqp/koreader-base,houqp/koreader-base,koreader/koreader-base,NiLuJe/koreader-base,Frenzie/koreader-base,houqp/koreader-base,NiLuJe/koreader-base,Frenzie/koreader-base