OpenSystemsDevelopment / qpdf

…, replace direct calls with `QIntC` equivalents, and clean up `QPDF.hh`.

… shared helper retrieval, validation methods, and update usages across the codebase. Remove unused test coverage entries.

…t. Add shared helper retrieval, validation methods, and update usages across the codebase.

…le handling. Add shared helper retrieval, validation methods, and update usages across the codebase.

This change updates all occurrences of `std::endl` to `\n` across various files for improved efficiency and consistency. It reduces unnecessary flushing of output buffers associated with `std::endl` while maintaining the same output format.

Simplified checks for empty containers and strings across the codebase using the `.empty()` method. This improves code readability and adheres to best practices for checking emptiness.

Converted multiple occurrences of `count()` to `contains()` throughout the codebase where the goal was to check key existence in containers. This improves code readability and aligns with modern C++ practices, particularly with C++20, making the intent more explicit and potentially aiding performance.

Except for virtual functions to avoid the need for users to update code.

This improves indentation of long strings. This commit also fixes some
trailing whitespace in ChangeLog.

Accept --file and --range as named parameters in additional to
allowing positional arguments. This is in preparation for adding
additional flags.

By combining --linearize with --compress-streams=n, we ensure that no
new compressed data will appear in linearized output, which makes the
output independent of zlib's output. There are other tests to ensure
that linearization works correctly with compression. This commit
involves changing some test outputs and test code as well just
updating test suites.

Fix all tests where the only required fix is to run qpdf-test-compare
instead of doing a simple file comparison.

Switch output to QDF for easier diffing
Simplify input image
Reduce decimal places

This works around an issue were, for certain versions, the mingw32
tests failed because of irrelevant floating point rounding issues in
the test output.

Use 'QPDFObjGen const&' instead of 'int, int' in signature.