Vpype

**Note**: This is the last version of *vpype* to support Python 3.6.

New features and improvements:
* Viewer improvements:
* Added rulers with dynamic scale to the display (can be optionally hidden) (199)
* Added metric and imperial unit system (in addition to pixels), used by the rulers and the mouse coordinates display (199, 205)
* Adjusted the size of the mouse coordinates text on Windows (199)
* Added support to adjust the scale of the UI via `~/.vpype.toml` (203)

This is achieved by adding the following lines to your `~/.vpype.toml` file:
toml
[viewer]
ui_scale_factor = 1.5

A value of 1.5 may be useful on some Windows configurations where the default UI is very small.

Bug fixes:
* Fixed issue on Linux where `show` would revert to the classic viewer due to a `libX11` discovery issue (206)

API changes:
* Renamed `vpype.CONFIG_MANAGER` in favour of `vpype.config_manager` (existing name kept for compatibility) (202)

New features and improvements:
* Python 3.9.1 (or later) is finally supported and now is the recommended version (115)
* Viewer improvements:
* The viewer will now keep the page fitted to the window when resizing, until manually zoomed and/or panned (193)
* Significantly optimized launch and setting changes times (184, 195)

Bug fixes:
* Various documentation fixes and improvements:
* improved the `layout` command's help text
* improved the cookbook section on using `GNU parallel` (108)
* fixed typos related to the `layout` command in the cookbook (186, thanks to f4nu)

API changes:
* Added support for a sidebar in the viewer (194)

New features and improvements:
* Added new `layout` command (168)

This command automates the page layout process on a specified the page size by centering the geometries (with
customizable horizontal and vertical alignment) and optionally fitting to specified margins. It intends to supersede
`write`'s layout options (i.e. `--page-size` and `--center`) in more intuitive way. In particular this command
acts on the pipeline rather than on the output file so its effect can be previewed with the `show` command.

* (Beta) Complete rewrite of the viewer underlying the `show` command (163)
* fully hardware-accelerated rendering engine
* smooth zooming and panning, with touchpad and mouse support
* preview mode with adjustable pen width and opacity
* outline mode with optional colorful and point display
* optional pen-up trajectories display
* per-layer visibility control
* interactively adjustable display settings

**Note**: This new viewer is a beta feature and will evolve in future versions. Your feedback is welcome. The current, matplotlib-based viewer is still available using `show --classic`.

* Added support for arbitrary paper size to `write`'s HPGL output (configuration for the Calcomp Designmate included, check the documentation for details) (178)
* Added large format paper sizes (A2, A1, A0) (144)
* The `splitall` command will now filter out segments with identical end-points (146)
* Minor loading time improvement (133)

Bug fixes:
* Various documentation fixes (170, 172, thanks to theomega)

API changes:
* Added the new viewer engine and Qt-based GUI (163)

Hot fix:
* Fixed systematic crash with `read` command due to bad dependency version (140)

New features and improvements:
* A Windows installer is now available (120)
* HPGL output: `--page-size` is no longer mandatory and `write` will try to infer which paper to use based on the current page size (132)
* Added `reverse` command (129)

Bug fixes:
* Fixed crash for SVG with <desc> element (127)
* Fixed an issue where output HPGL file could be empty (132)