GitLab

* Capture new PID from fork (nice for debugging)
* Start debugger paused so we can debug the startup process
* Reformat GNUmakefile to highlight similarities in the disk images created
* Update README.md to clarify that we build two disk images
* Use `%bl` when notifying BIOS of Long Mode
* Correct filenames in comments
* Add comments to describe boot process
* Add function to test memory mapping size
* Explain that `panic()` will produce a page fault if there is no console
* Debug CHICKADEE_FIRST_PROCESS
* Use spinlock for logging to avoid interleaving output

The previous sys_panic() output tended to scroll important stuff
off the top of the screen.