Audacity 3.4.0

What's new in this version:

Major changes:
- Music workflows
- Audacity now features several music related features, such as switching between hh:mm:ss time and Beats & Measures, and time-stretching clips to align them to a song's tempo
- Time stretching
- Hold Alt (macOS: Option) while hovering over the top third of a clip edge to stretch it.
- New exporter
- Audacity now features a new export window with easier access to options such as sample rate and custom mapping (for 5.1 or 7.1 audio). Additionally, the "Browse" button uses the native file browser now!

Other changes:
- For MP3, Audacity now always uses Joint Stereo mode, which always delivers the best possible quality
- Simplified pasting logic
- Simplified stereo tracks. Left and right channels now always have synchronized clip starts and ends, and the same sample rate in both channels
- Added cursors trimming and stretching left and right, and changed the I-beam cursor to be less similar to either
- When importing audio, the project sample rate no longer changes
- The spectrogram colors are now perceptually uniform, and the colormap has gotten a name: Roseus. It also can be used for dataviz outside of Audacity
- New defaults: The Time Signature toolbar now gets shown, the solo button is set to multi-track mode, time tracks have a wider starting range
- Unsquished the Audacity logo found in some places of the app
- Clicking on the border of two clips no longer merges them
- Overdubbing on Windows fails with WASAPI with default Recording device
- Built-in Opus support

Libraries:
- lib-time-and-pitch implements a time stretching algorithm originating in Staffpad
- Audacity now uses Conan 2
- Continued extracting code into libraries and modules, especially in the context of importing and exporting

Fixed:
- --nogap metadata no longer is ignored
- fixed a crash with LV2 plugins
- fixed some crashes related to macros
- fixed a crash when pasting in certain configurations
- Accessibility: GUI can be disabled again for VST2 plugins
- Accessibility: Restored window control IDs, improving NVDA compatibility
- fixed a crash on launch on OSX 10.9