tigefa4u projects Trac

sqlalchemy:
* revert changes to `setup.py`
* actually delete file `patch` just made empty

sqlalchemy: initial working implementation

create sandbox branch for SQLAlchemy support

VcRefactoring: support for scoped repositories which are not full self-contained (#1830)
* don't store base paths which are coming from outside of the repository scope
* introduced specialized versioncontrol related exception:
* `NoSuchChangeset`
* `NoSuchNode`
* refactored the `TracError` usage to either use one of the above or the use the `TracError(...)` style instead of the `TracError, ...` style
* fix a potential bug when getting the change summary from the Changeset.get_changes

Thanks to Manuzhai for the initial work on this topic.

Follow-up to r2990: don't automatically enable the version control plugin during initenv. Instead simply warn the user about the repository being unavailable, if this is the case

Merge the current status of the VcRefactoring in trunk
(log:sandbox/vc-refactoring@...:2989)

Summary of the new features:
* support for extra changeset properties (see `Changeset.get_properties`)
* support for hex digits in changeset identifiers

The [source:sandbox/mercurial-plugin@...] should work on trunk, now.

VcRefactoring:
* fixed display of multiple extra changeset properties
* allow to quickjump for alphanumerical changesets (e.g. `[3a56574f329a]` or `[tip]` for TracMercurial, `[head]` for TracSubversion)

TracMercurial: follow-up to the rename done in [2985]

TracMercurial: complete the move started in [2986]

VcRefactoring: backout the setuptools namespace stuff. Instead, use the convention to name the version control backend plugin using the `tracvc.` prefix.