update .i files for new version of SWIG

[goretkin]

I just tried to install pybox2d in a brew-install of python and swig

$ swig -version

SWIG Version 3.0.7

and this is the result

python setup.py build
Using setuptools (version 0.6).
running build
running build_py
copying library/Box2D/__init__.py -> build/lib.macosx-10.9-x86_64-2.7/Box2D
running build_ext
building 'Box2D._Box2D' extension
swigging Box2D/Box2D.i to Box2D/Box2D_wrap.cpp
swig -python -c++ -IBox2D -small -O -includeall -ignoremissing -w201 -globals b2Globals -outdir library/Box2D -keyword -w511 -D_SWIG_KWARGS -o Box2D/Box2D_wrap.cpp Box2D/Box2D.i
Box2D/Box2D_joints.i:505: Error: Unknown SWIG preprocessor directive: Some (if this is a block of target language code, delimit it with %{ and %})
Box2D/Box2D_joints.i:506: Error: Unknown SWIG preprocessor directive: have (if this is a block of target language code, delimit it with %{ and %})
Box2D/Box2D_joints.i:525: Error: Unknown SWIG preprocessor directive: Ratio (if this is a block of target language code, delimit it with %{ and %})
error: command 'swig' failed with exit status 1

which I think is caused by the same issue as described here: MTG/gaia#13

[goretkin]

I was on another branch of pybox2d. I just tried building from master and it succeeded. Indeed the changes are in there! Sorry, I thought I had looked, but here it is: 18ad008

Thank you!