* Add script ERP5Site_loadEmailThreadData to load the data of selected email. This script is used to open one email in the current page.
* Refactor ERP5Site_createNewEmailThread to do not create a new email if  it already exist one Email Thread created.

git-svn-id: https://svn.erp5.org/repos/public/erp5/trunk@43274 20353a03-c40f-0410-a6d1-a30d3c3de9de