[FIX] tools: accept multilines on_change

Allow to write on_change on several lines (accepted by view parser but was not
by yaml parser, making false positive at 595216b)

openerp/tools/yaml_import.py

@@ -427,7 +427,7 @@ def process_val(key, val):
 
                     if not el.attrib.get('on_change', False):
                         continue
-                    match = re.match("([a-z_1-9A-Z]+)\((.*)\)", el.attrib['on_change'])
+                    match = re.match("([a-z_1-9A-Z]+)\((.*)\)", el.attrib['on_change'], re.DOTALL)
                     assert match, "Unable to parse the on_change '%s'!" % (el.attrib['on_change'], )
 
                     # creating the context