Imports may un-escape backslashes and single quotes in strings.

This is an edge-case problem but none-the-less one that we ran into recently.

If you have a string that contains escaped single quotes, those single quotes become un-escaped upon import.

For example, create a new story node with the following body:

A story with \' \" \\

Then import it at admin/content/node. The resulting body is now:

A story with ' \" \

So as you can see, we loose the "escaping" on single quotes and backslashes. It's not really escaping within the node body of course, but we have had unintentional data modification.

This patch replaces the use of addslashes() with strtr() and only escapes the only character that matters: a single quote. It also makes it so we don't have to do any string correction on import at all, which is a nice bonus.