EpsFilePlugin Speed improvements. 

Fix for #838. 

@karstenw -- Sorry on the delay for this. This should be what we've discussed in #838, stripped down to remove excess code in a few places. 

* Universal line ending wrappers are called for files
* There's a shim for doing line endings for BytesIO/StringIO. 
* The initial read is done on the bare fp, so no line ending translation is done. 
* If it's a file, ghostscript should use the file without copying, if not, it writes to a temp file first.