Fix error message of StringAttributeMatch Constraint incorrectly renamed after migration to ZODB (78e2ae3).
Implement migration of StringAttributeMatch from filesystem to ZODB.
Fix migration of some Constraints.
Invalid error message returned in CategoryMembershipArity Constraint.
Fix loading of Portal Type after renaming of SynchronisationTool.
After upgrade, VCS is used instead of SVN in erp5_forge (migration has not been implemented).

If an user has set SVN working copies in its preferences, it cannot be
modified anymore after upgrade.
Allow to specify bt5 which are not going to be upgraded (meaningful for master data for example).
Fix dead ProxyFields.

PasswordTool_viewResetPassword/text_content from erp5_core wrongly requires
Field Library in erp5_web and EmbeddedFile_view/my_description from erp5_base
wrongly requires Field Library in erp5_dms.
Upon Business Path Item installation, update Local Roles of objects whose Portal Types defines Roles.

Before, Local Roles were not updated upon Path Item installation, thus leading
to security issues (such as Trade Model Line). This avoids ugly hacks in
Upgrader and in tests as well.
Avoid running out of file descriptors when backing up many objects in the trash upon bt5 installation.

Before, when installing a bt5 whose format has changed, many subobjects may
end up being backup up, but it keeps one FD per subobject, thus easily
reaching the limit of 1024 FDs (as given by ulimit -Sn/-Hn).

This is a followup of b71e5a7 specific to TrashTool as that commit seems to
only fix the issue when TrashTool is not used.
Add unit test helper to get the checkConsistency() error messages as string.
If a Live Test is interrupted, MailHost may have not been restored yet.
Store Live Tests log in INSTANCEHOME/var rather than in a StringIO.

This avoids copying/pasting the content of the form and also keep records for
later inspection.
Two hours may not be enough to run Functional Tests so increase timeout.