Remove the submodule for cgen

We do not need it.

.gitmodules

-[submodule "python/cgen"]
-	path = python/cgen
-	url = https://github.com/inducer/cgen.git
 [submodule "python/loopy"]
 	path = python/loopy
 	url = https://github.com/dokempf/loopy.git

python/CMakeLists.txt

@@ -10,7 +10,6 @@ create_virtualenv_wrapper(COMMANDS python -m IPython notebook
 
 # Install all the external packages that we have as submodules
 dune_install_python_package(PATH pymbolic)
-dune_install_python_package(PATH cgen)
 dune_install_python_package(PATH loopy)
 dune_install_python_package(PATH ufl)
 

cgen @ 716ea0fd

-Subproject commit 716ea0fda102bc5b829122dd578566ce42f37912