FIX: Multi-line search text should be passed as a joined single argument, not one search per line

For opening files, it makes sense to assume line-based input (i.e. one file per line), but when doing web searches, we'd rather have the whole text passed as-is. Many error messages and stack traces span multiple lines!
This gets rid of the xargs, but we can also drop the chdir to the pane's CWD; unlike filespecs, the web search argument is not dependent on the current path (and the search command most likely is found through PATH).

Author: inkarkat

open.tmux

@@ -36,7 +36,7 @@ search_command_generator() {
 	local command_string="$1"
 	local engine="$2"
 
-	echo "xargs -I {} tmux run-shell -b 'cd #{pane_current_path}; $command_string $engine\"{}\" > /dev/null'"
+	echo "$command_string \"$engine\$(cat)\" >/dev/null"
 }
 
 generate_open_command() {