Lots of little async cleanups

src/strategies/default.zsh

@@ -15,6 +15,6 @@ _zsh_autosuggest_strategy_default() {
 	local -a histkeys
 	histkeys=(${(k)history[(r)$prefix*]})
 
-	# Echo the value of the first key
-	echo -E "${history[$histkeys[1]]}"
+	# Give back the value of the first key
+	suggestion="${history[$histkeys[1]]}"
 }

src/strategies/match_prev_cmd.zsh

@@ -47,6 +47,6 @@ _zsh_autosuggest_strategy_match_prev_cmd() {
 		fi
 	done
 
-	# Echo the matched history entry
-	echo -E "$history[$histkey]"
+	# Give back the matched history entry
+	suggestion="$history[$histkey]"
 }