[ADD] crm_project_issue: link module to create lead from issues and issues from lead
[ADD] change the link between lead and issue. Now : transfrom a lead into a issue and modify the mail thread
[Fix] : external id not found in view
[Change] getting
[FIX] : modified according to tde's remarks
[FIX] modified with the remarks of apr
[FIX] : tde's last remark correction
[MERGE] [ADD] crm_project_issue module: create issues from leads.
This bridge and optional module add a button on the lead form view to
allow users to create issues from leads. The lead is distroyed during
the operation. All communication history is kept and transferred to the
new issue.