[mkgmap-dev] options update

Here's a patch that: adds some options to the help file improves wording in the help file adds TODO items in the help file when I think something should be there but don't know the answer a bit of general cleanup in the help file removes option description from README, pointing people to the help file and README.examples I've gone through some of my saved mail messages - I'm trying to work the helpful hints in them into the docs so I no longer need to save the messages.