Workaround for Termux backup size issue

Optionally export backups AES256-encrypted with ccrypt.

lzma|xz, zip and zst|zstd archives are also known by migrator.
This means, specifying the extraction method is optional if <program> is available and in $PATH.
Among the supported programs, only pigz and zstd are not generally available in Android/Busybox at this point.
However, since pigz is most often used as a gzip alternative (faster), its .gz archives can also be extracted by gzip itself.

General fixes & optimizations

The default compression method is <none> (faster, output: .tar file). Method here refers to "<program> <options>" (e.g., "zstd -1v").
The decompression/extraction method to use is automatically determined based on file extension (supported extensions: tar, tar.bz*, tar.gz* and tar.lzo*). The user can supply an alternate method for decompressing other archive types.

--list shows install status as well.
Option to restore only apps that are not installed: "-rn".
Updated data migration tutorial and Tasker setup instructions - export/import to/from external storage included.

Cleaner export/import interface.
Export/import uncompressed archives (-c -).
Fixed settings restore.

Using /data/migrator/ as the new data directory. Android 10 complains when it's placed anywhere in /data/media/.
$version is included in verbose.

NOTE

To restore backups from the old location, use the version that made such backups (/data/media/migrator/local/migrator.sh).
Alternatively, you can move migrator's data folder to the new location (mv /data/media/migrator /data/).

WARNING

The ROM migration process has two additional steps to account for the new backup location.
Failing to follow the instructions carefully will lead to data loss!

Auto backup config suports a new parameter: cmd="post bkp cmd".
Backup/restore apps' device-encrypted data as well (/data/user_de/0/<pkg>).
General fixes & optimizations
Replaced all instances of ${0##*/} with M in README.md.
The sysdata list includes more Bluetooth and accounts configuration files.

Automatic backups (Magisk, init.d and Tasker flavors)
Major fixes & optimizations
More comprehensive `--list`
System data backup/restore sub-option is now D (formerly S).
README.md has a copy of the help text.
Updated documentation (ROM migration instructions, automatic backup configuration and more).
Verbose is redirected to /dev/migrator.log, which can be exported to /sdcard/migrator.log.bz2 with `M -L`.
Works in recovery environments (particularly useful for emergency backups).

General fixes & optimizations
Backup/restore magisk data's SELinux contexts (ditch the hard-coded `u:object_r:system_file:s0`).
Mark all restored apps as installed from Google Play Store.

WARNING
This version will fail to restore magisk data backed up with previous builds.
Use the backup creator (backed itself up too): `/data/media/migrator/*/migrator.sh`.

Backups are no longer moved to bkp.old/.
Major fixes & optimizations
More flexible backup/restore options (e.g., app only, data only)
New backups replace old ones.
Updated help text.

WARNING
This version will fail to restore data backed up with previous versions.
Use the backup creator (backed itself up too): `/data/media/migrator/bkp*/migrator.sh`.

Fixed "lzop, parameter not set" and SSAID related issues.

WARNING
This version will fail to restore data backed up with previous versions.
Use the backup creator (backed itself up too): `/data/media/migrator/bkp*/migrator.sh`.

`--export` and `--import` are more advanced and flexible. Refer to the help text for details.
`--export` creates individual archives for each backup.
Automatic `M --ssaid` runs syncronously.
Enhanced SSAID restore.
Major fixes & optimizations
Updated help text.

WARNING
This version will fail to restore data backed up with previous versions.
Use the backup creator (backed itself up too): `/data/media/migrator/bkp*/migrator.sh`.

Backup app data modes (ditch hard-coded values).
Backup battery optimization whitelist (deviceidle.xml) as part of system data.
Backup Magisk data modes and ownership.
Fixed wifi hotspot settings backup not working.
General optimizations
Perform stricter safety checks during SSAIDs restore.

WARNING
  This version will fail to restore data backed up with previous versions.
  Use the backup creator (backed itself up too): `/data/media/migrator/bkp*/migrator.sh`.

Restore app specific Android IDs.
Fixed accounts backup not working.
Optimized parsing of options to avoid conflicts with certain package names.