[FIX] view_form: use the reference of menu from the instance, not from the widget ancestors
Fixes #1024: when using a formview on a non trivial way, the reference of the menu using the widget ancestors may be wrong
[FIX] project: inappropriate signature in project.task.work.unlink()
[FIX] exception rendering with pretty printed XML

had not been migrated to lxml
[FIX] ensure all g_inner content is correctly encoded

fixes #1130

* provided `inner` data may or may not have been encoded
* `element.text` is either ascii-compatible `str` or `unicode` when
  non-ascii-compatible, which could force the decoding of utf8-encoded content
  during g_inner's join
Merge pull request #1097 from odoo-dev/8.0-fix-view-editor-sle

[FIX] view_form: use the reference of menu from the instance, not from t...