Add visual mode investigate on selected text

Select visual text based on http://stackoverflow.com/a/6271254/889972

README.md

@@ -15,7 +15,8 @@ By default investigate is mapped to `gK`. If you want to set up your
 own mapping you should use something like this:
 
 ```
-nnoremap <leader>K :call investigate#Investigate()<CR>
+nnoremap <leader>K :call investigate#Investigate('n')<CR>
+vnoremap <leader>K :call investigate#Investigate('v')<CR>
 ```
 
 With this mapping, using <leader>K when your cursor is on a specific

autoload/investigate.vim

@@ -82,15 +82,32 @@ function! s:BuildCommand(filetype, word)
 endfunction
 " }}}
 
+" Get selected text from buffer ------ {{{
+function! s:get_selected_text()
+  let [lnum1, col1] = getpos("'<")[1:2]
+  let [lnum2, col2] = getpos("'>")[1:2]
+  let lines = getline(lnum1, lnum2)
+  let lines[-1] = lines[-1][: col2 - (&selection == 'inclusive' ? 1 : 2)]
+  let lines[0] = lines[0][col1 - 1:]
+  let text = substitute(join(lines, "\n"), '[\n\r]\+', ' ', 'g')
+  return substitute(text, '^\s*\|\s*$', '', 'g')
+endfunction
+"}}}
+
 " The actual open command for mapping ------ {{{
-function! investigate#Investigate()
+function! investigate#Investigate(mode)
   let l:filetype = &filetype
   if empty(l:filetype)
     echomsg "You must set your filetype to look up documentation"
     return
   endif
 
-  let l:word = expand("<cword>")
+  if a:mode ==# 'n'
+    let l:word = expand("<cword>")
+  else
+    let l:word = s:get_selected_text()
+  endif
+
   if empty(l:word)
     echomsg "Put your cursor over a word to look up it's documentation"
     return

plugin/investigate.vim

@@ -18,5 +18,6 @@ if filereadable(g:investigate_local_filename)
 endif
 
 if !hasmapto("investigate#Investigate()") && empty(mapcheck("gK", "n"))
-  nnoremap gK :call investigate#Investigate()<CR>
+  nnoremap gK :call investigate#Investigate('n')<CR>
+  vnoremap gK :call investigate#Investigate('v')<CR>
 endif