v0.12.0

• Revised minimum Rust version to 1.54
• Bumped env_logger and removed dependency on indoc to make the transitive dependency tree smaller
• New APIs in autocxx_build; old ones still exist but are deprecated - move to the new ones
• Synthesize make_unique for types with default constructors (fixes #122)
• Add an experimental "dynamic discovery" mode (see autocxx_build::Builder::auto_allowlist) which enables you to remove the generate directives
• Subclasses:
  • Simplified example by adding prelude and some derive macros
  • Removed the need to explicitly call a C++ peer constructor; the subclass codegen now does this automatically unless there are multiple or complex constructors in which case you'll need to implement a trait to choose
  • Improved panics on re-entrancy and similar error states
  • Filed issues for all known limitations and mentioned in documentation
• Much documentation
• Filenames of generated .rs files on disk have changed - they're no longer based on a hash of the directives. This should reduce filesystem pollution through leaking old versions.