Changes the current normal-mode mappings <leader>sw / <leader>sW to only
display matches surrounded by word boundaries. Also adds the equivalent
visual-mode mappings to allow searching for the current selection.
Selection searching does not consider word boundaries, so highlighting a
single word and searching for it will produce the same results as the
word-under-cursor searching did before this change. This allows the user
to easily choose whether or not to include word boundaries in their
search.
Sam Amis