tools/chdman.cpp: Added --hunksize/-hs option for createdvd command and
default to 4K hunks (2 sectors, same size as hard disk hunks). Also
removed --outputbin/-ob option from extractdvd command - it did nothing
as it's CD-specific.
docs: Added preliminary chdman documentation. Most common options have
at least basic descriptions, supported options are listed for all
commands, and supported compression algorithms are described.
docs: Cleaned up heading levels in tools section.