Pyarmor

* Fix sub-package could not import `pytransform` when it's obfuscated by `--bootstrap 3` in super mode
* For Windows platform, add new modes `--advanced 3` and `--advanced 4` to enable vm protection.
Refer to https://pyarmor.readthedocs.io/en/latest/mode.html#vm-mode
* The default value of option `obf-mod` is set to `2`
* Add new platform `musl.mips32` for MIPS32 with musl-libc
* Add new platform `linux.mips64` and `linux.mips64el`
* Fix super mode crash issue for `linux.armv7` and `linux.aarch32`

* Fix super mode crash issue for Python37/38 in Windows
* Fix command `pack` issue: the obfuscation option `--enable-suffix` doesn't work

* Fix super mode crash issue for Coroutine functions
* Fix super mode exception issue
* Fix restrict mode 3/4 doesn't work in some cases
* Fix super mode will complain of `insert one redundant line '[None, None]'` issue

From this version, only 2 runtime files are required for non-super mode:

* pytranform.py
* _pytransform.so/dll/dylib

Most of the algorithm are refined to improve the security.

* Refine the algorithm to improve security and performance
* Refine default cross protection code
* Refine runtime files, remove `license.lic` and `pytransform.key`
* Refine pack command
* Refine the obfuscating process for cross platforms
* Refine `benchmark` command, and new option `--advanced`
Refer to https://pyarmor.readthedocs.io/en/latest/performance.html
* Add platform `musl.mips32` for MIPS32 with `musl`
* Add common options `--boot` for special cross platform obfuscating
* Rename platform name `alpine.*` to `musl.*`

* Fix cross platform bug: in Windows it may raise exception
`can't open file '...\Scripts\pyarmor': [Errno 2] No such file or directory`
* Fix super mode bug: in some cases super mode will raise exception `unknown opcode`

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