### Changed
- Moved `\tl_if_single_token:n(TF)` to stable
- Moved `\file_get_mdfive_hash:nN(TF)`, `\file_get_size:nN(TF)`
and `\file_get_timestamp:nN(TF)` to stable
- Moved `\file_if_exist_input:n` and `\file_if_exist_input:nF` to stable
- Moved `\file_input_stop:` to stable
- Moved `\peek_N_type:TF` to stable
- Experimental `\driver_pdf_compress_objects:n` replaces
`\driver_pdf_objects_(en|dis)able:`
### Fixed
- Support for ConTeXt from mid-December 2018
- Infinite loop in some cases in DVI mode due to link-breaking code
- Category code of output from `\char_<target>_case:N`, and
same issue in `\str_<target>_case:n`
- Some issues in `dvisvgm` driver
### Added
- Experimental support for a range of PDF concepts at the lowest
(driver abstraction) level
- New `l3legacy` module containing
- `\legacy_if:n(TF)`
- `\char_str_<target>_case:N`
- `.muskip:N` property
- Experimental driver-level interfaces for image inclusion
- Experimental `\ior_shell_open:Nn`
a4be62cc8a