Since 76cc938e we have diffs each time we edit ZSQL Methods. This is a "big commit" to change all remaining ZSQL methods. I checked diffs one by one, but I would appreciate others check this as well and confirm that it's OK to do so.

From the root of repository, I did :

```
grep -rl Products.ZSQLMethods.SQL  . | grep '\.xml$' | xargs ~/bin/zsql_backslash_n.py
```

With a script containing
```python

from lxml import etree
import sys

for filename in sys.argv[1:]:
  with open(filename) as f:
    tree = etree.parse(f)
    root = tree.getroot()
    for el in tree.xpath('//item/key/string[text() = "arguments_src"]/../../value/string'):
      if el.text:
        el.text = el.text.replace(r'\r\n', r'\n')

    # force <string> element to have a text, so that they export as <string></string> and not <string/>
    for el in tree.xpath('//string[not(text())]'):
      el.text = ''

  with open(filename, 'w') as f:
    f.write(
        '<?xml version="1.0"?>\n'
        + etree.tostring(root, pretty_print=True, encoding="utf-8"))

  print filename
```
( script snippet: $277 )

/cc @jm @georgios.dagkakis @Nicolas

/reviewed-on !496

Conflicts:
	product/ERP5/bootstrap/erp5_mysql_innodb_catalog/CatalogMethodTemplateItem/portal_catalog/erp5_mysql_innodb/z_getitem_by_path.xml
	product/ERP5/bootstrap/erp5_mysql_innodb_catalog/CatalogMethodTemplateItem/portal_catalog/erp5_mysql_innodb/z_getitem_by_uid.xml
	product/ERP5/bootstrap/erp5_mysql_innodb_catalog/CatalogMethodTemplateItem/portal_catalog/erp5_mysql_innodb/z_produce_reserved_uid_list.xml