Ratarmount

- Fix "BLOB longer than INT_MAX bytes" error for .gz archives larger than ~400GB.
- Add missing "dataclasses" dependency for Python 3.6.
- Open SQLite index read-only to allow multiple ratarmount instances to use it.
- Raise exception if SQLiteIndexedTar cannot read given file object.
- Warn on newer index versions.
- Add support for "--index-name :memory:" to create in-memory indexes.

- Fix SQLiteIndexedTar class when being called with a file object.
- Add -P argument option to activate the parallel BZ2 decoder of indexed_bzip2 1.2.0.
- Add --lazy option, which works in tandem with --recursive, and bind mounted folders.
TARs inside the source folder will be mounted only after the first access to it through the mount point.
- TARs containing hard links to files with exactly the same name will be interpreted as referring
to a prior version of that file.

- Add CLI options --index-file and --index-folder to specify an index location or folder.
- Add support for zstd compressed TARs.
- Add support for xz compressed TARs when compressed with pixz or pxz or similar tools
limiting the block size.
- Fix index location check not accounting for SQLite special requirements.
- Add warnings for when the existing index was created with different arguments,
e.g., without --recursive, even though --recursive was requested.
- Add specialized exceptions used by ratarmount.
- Add recursive mounting for folders in order to mount all contained TARs.

- Fix broken CLI and add test for it.

- Fix bug with filename encoding on some special characters like accented vowels or umlauts.
- Add support to mount simple .gz or .bz2 files, which are not compressed TARs.
- Fix number of hardlinks being always shown as 2. Changed to show 1.
- Fix wrong size reporting when index size has changed.
- Fix blocksize and therefore `du` results always showing 0.
- Add command line option to turn on modification timestamp checking.
- Add command to mount recursive tars at folders where the .tar extension is stripped.
- Fix recursion limit hit when mounting a TAR with more than or equal 1000 contained TARs.

- Add support for sparse files inside the TAR.
- Automatically detect if the TAR file has grown since the last index creation.
- Add support for truncated TAR files, e.g., during downloading.
- Add support for concatenated TAR files.
- Add support for hardlinks in the TAR file.
- Add support for union mounting.
- Add support for accessing older versions of a file if the TAR contains multiple versions.
- Detect changes in TAR files and recreate the index if so.
- Remove support for old non-SQLite index backends.