Drop legacy submodules, empty README and ORM leftovers

.gitattributes

@@ -2,7 +2,6 @@
 /docs export-ignore
 .gitattributes export-ignore
 .gitignore export-ignore
-.gitmodules export-ignore
 .appveyor.yml export-ignore
 .travis.yml export-ignore
 build.properties export-ignore

.gitmodules

-[submodule "docs/en/_theme"]
-    path = docs/en/_theme
-    url = git://github.com/doctrine/doctrine-sphinx-theme.git

tests/.gitignore

-Doctrine/Tests/Proxies/
-Doctrine/Tests/ORM/Proxy/generated/
-Doctrine/Tests/ORM/Tools/Export/export

tests/README.markdown

-# Running the Doctrine 2 Testsuite
-
-## Setting up a PHPUnit Configuration XML
-
-..
-
-## Testing Lock-Support
-
-The Lock support in Doctrine 2 is tested using Gearman, which allows to run concurrent tasks in parallel.
-Install Gearman with PHP as follows:
-
-1. Go to http://www.gearman.org and download the latest Gearman Server
-2. Compile it and then call ldconfig
-3. Start it up "gearmand -vvvv"
-4. Install pecl/gearman by calling "gearman-beta"
-
-You can then go into tests/ and start up two workers:
-
-    php Doctrine/Tests/ORM/Functional/Locking/LockAgentWorker.php
-
-Then run the locking test-suite:
-
-    phpunit --configuration <myconfig.xml> Doctrine/Tests/ORM/Functional/Locking/GearmanLockTest.php
-
-This can run considerable time, because it is using sleep() to test for the timing ranges of locks.
\ No newline at end of file