When enabled, the assembled code will be returned as bytes (str on
Python 2) instead of a list of integers, this is more memory efficient,
faster (It's created using ctypes.string_at instead of a loop in
Python), and more convenient since that's the type that most code that
works with bytes in Python expects (That includes capstone).

Defaults to `False` for backwards compatibility, since changing the
return type is a breaking change.

using `data_files` dict prefixed with
`SITE_PACKAGES = os.path.join(get_python_lib(), "keystone")` is not
portable, see #235 and #297 for details. Regular setup configuration does
not work, e.g., specifying `package_data` etc, since that only affects
`sdist`.

The fix is a hack: customize `install_lib` to explicitly copy the file
into keystone install dir.

update bindings to add KS_OPT_SYM_RESOLVER. Python binding now supports this option. see sample.py for example

* ks_free: The 'p' argument should have type unsigned char* to match the type of the 'encoding' argument to ks_asm

handle equal directive. this fixes c-crashes/crash-12-x64-cannot-set-a-variable-that-has-already-been-used.c

handle error in applyFixup(). this fixes c-crashes/crash-23-x64-value-does-not-fit-in-the-fixup-field.c

x86: report unsupported instructions in encodeInstruction(). this fixes c-crashes/crash-24-x64-not-is16bitmemoperand.c

propagate the error of missing symbol back to ks_asm(). this adds new error code KS_ERR_ASM_SYMBOL_NOTFOUND. fix issue #61

add error code KS_ERR_ASM_SYMBOL_REDEFINED to report redefined symbols. also updated all the bindings after this