Reanme *_dimension -> *_iname.

MEMO

doc/reference.rst

examples/matrix-mul.py

loopy/__init__.py

loopy/creation.py

loopy/cse.py

loopy/padding.py

loopy/preprocess.py

proto-tests/test_dg.py

proto-tests/test_fem_assembly.py

proto-tests/test_sem.py

proto-tests/test_sem_tim.py

proto-tests/test_tim.py

test/test_linalg.py

test/test_loopy.py

test/test_nbody.py

test/test_sem_reagan.py