* Added support for handling case-insensitive and case
sensitive checkpoints. This works if $P4DBIN is
a symlink rather than a wrapper supplying '-C1', as
the need for '-C1' is dynamically detected. (This was
driven by a need to incorporate load_checkpoint.sh into
case conversion orchestration scripts using p4migrate).
* Added '-r' flag to load checkpoint into P4ROOT only,
* Added '-b' flag to restart broker at the end.
* Normalized to template.sh structure, with typical
benefits (enhanced command line parsing, standard usage
message, better documentation).
* Added check for missing certificate.txt if using SSL.
* Made shellcheck v0.6.0 compliant.