0.19.0 release

[TTWNO]

• Bump minor versions across crates
• realize there are unreleased breaking changes, and add major version bump

[TTWNO]

• Fixes marshalled/unmarshalled signature issue with Cache events.
• Spelling fixes throughout documentation.
• Add more documentation throughout.
• Unnest large macros into smaller, more documented macros.
• Simplify event marshaling code.
• Document private items in CI.
• Add new Live type, and Announcment signal new to AT-SPI.

[codecov]

Codecov Report

Merging #137 (16a17c0) into main (2ed88ba) will increase coverage by 0.03%.
The diff coverage is n/a.

@@            Coverage Diff             @@
##             main     #137      +/-   ##
==========================================
+ Coverage   89.98%   90.01%   +0.03%     
==========================================
  Files          39       39              
  Lines        3176     3176              
==========================================
+ Hits         2858     2859       +1     
+ Misses        318      317       -1     

see 1 file with indirect coverage changes

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