Main

Minor code cleanup. Bump version to v0.5.1.

Replace boost::filesystem with std::filesystem. Replace
boost::program_options with CLI11. Rename ProtectedAndSynchronizedQueue
to ProtectedQueue. Fix error with JPEG_REGEX. Bump version to v0.5.0.

Update PCA CMakeLists.txt. Build libpackjpg as a dependent external
project.

Use computed library path for install.

Adding missing include.

Add link time optimization to compiler (linker) flags.

Fixing items suggested by clang-tidy.

Minor formatting changes for running status output.

Adding non-verbose mode with "running" status information and progress
bar. Also added terminate function in preparation of adding proper
SIGINT handling.

Fix simple but nasty memory leak.