Determine correct library path on non-OS X systems

[bendyer]

From python/__init__.py:212–221:

    # Load the requested library and determine configuration parameters
    if implementation == "c":
        lib = os.path.join(os.path.dirname(__file__), "c", "libcukf.dylib")
    elif implementation == "c66x":
        lib = os.path.join(os.path.dirname(__file__), "ccs-c66x",
                           "libc66ukf.dylib")
    else:
        raise NameError(
            "Unknown UKF implementation: %s (options are 'c', 'c66x')" %
            implementation)

The .dylib extension is OS X-specific; we should work out what the correct library name is for the current platform, and automatically load it.

(Alternatively, try a bunch of common library file extensions and load the first found.)