release notes for cppcheck-2.9

- restored check for negative allocation (new[]) and negative VLA sizes from cppcheck 1.87 (LCppC backport)
- replaced hardcoded check for pipe() buffer size by library configuration option (LCppC backport)
- on Windows the callstack is now being written to the output specific via "--exception-handling"
- make it possible to disable the various exception handling parts via the CMake options "NO_UNIX_SIGNAL_HANDLING", "NO_UNIX_BACKTRACE_SUPPORT" and "NO_WINDOWS_SEH"
- detect more redundant calls of std::string::c_str(), std::string::substr(), and unnecessary copies of containers
- Add a `match` function to addon similiar to `Token::Match` used internally by cppcheck:
    - `|` for either-or tokens(ie `struct|class` to match either `struct` or `class`)
    - `!!` to negate a token
    - It supports the `%any%`, `%assign%`, `%comp%`, `%name%`, `%op%`, `%or%`, `%oror%`, and `%var%` keywords
    - It supports `(*)`, `{*}`, `[*]`, and `<*>` to match links
    - `@` can be added to bind the token to a name
    - `**` can be used to match until a token
- Add math functions which can be used in library function definition. This enables evaluation of more math functions in ValueFlow
- Further improve lifetim analysis with `this` pointers
- Propagate condition values from outer function calls
- Add debug intrinscs `debug_valueflow` and `debug_valuetype` to show more detail including source backtraces