Pyarmor

* Fix arch `ppc64le` could not work issue
* In `pack` command, clean build cache automatically before packing the obfuscated scripts

* Fix a crash issue in Darwin platform
* Fix super mode issue in Darwin: the obfuscated scripts report "image not found" (256)
* Document experiment feature: [how to protect data file](https://pyarmor.readthedocs.io/en/latest/advanced.html#how-to-protect-data-files)

* Fix `get_license_info` issue: the value of `CODE` is blank

* Add option `--with-license` in the command `build`
* Fix pack issue: the option`--with-license` doesn't work in super mode
* If the code object couldn't be obfuscated in advanced 2 (super mode), fix it automatically by inserting one redundant line `[None, None]` at the beginning of this code object
* Ignore case when checking mac address if the license is bind to network card
* Add key `ISSUER` in the return value of `get_license_info`

* Fix pack issue for Mac in super mode: `RuntimeError: unexpected pytransform.so`
* Fix pack issue for windows 32-bit system: the default license doesn't work in other machines, it complains of `License is not for this machine`

* Add common option `--home`, so PYARMOR_HOME can be set in the command line
* Fix pack issue: pack command may not work with super mode