Main

Correct installation of static library.

Correct library header install path.

Removing leading slash from install paths.

Use computed library path for install.

Adding libpackjpg statis library target.

Modernize packJPG CMakeLists.txt. Remove Boost dependency.

Adding update from github: https://github.com/packjpg/packJPG/commit/93a7dfbe1fb9aa2aee763cc5b8a16c14b2f66c8c

Add link time optimization to compiler (linker) flags. Also change
default install path to /opt/local.

Move includes to source file and add forward declarations in their place
so that the packjpg.h header can be used externally.

Fix library name and include path for install target.