[TYPO3-core] Remove / Cleanup sub-projects of Core

[Ernesto Baschny [cron IT]]

Hi,

on forge the "typo3v4-core" project has several sub-projects, usually
because features were developed by a certain team, had a separate
repository etc.

Some of them are still valid and make sense, basically because they are
linked into the core as a git submodule.

But others are just not needed anymore and in my opinion should be
integrated into the "Core". Here is a complete list and my opinion:

1) Keep these as is:

* DBAL
* Extbase MVC Framework
* Linkvalidator
* Team Resources
* Workspaces & Versioning

2) Move project to "Community Extensions":

* Advanced Frontend Editing

3) Remove:

by moving Issues to Core (creating new corresponding categories),
removing the obsolete repositories to avoid confusion (have been both
integrated as sysext directly into the core years ago already):

* Scheduler = Francois, what do you think?
* t3editor = Tobi, what do you think?

This would lessen confusion a bit on where to report bugs and lower
confusion because of obsolete and unmaintained code in the projects
repositories.

What is your opinion?

Cheers,
Ernesto