New help updates

As per IRC discussions, here is the pull request for these changes.  Note that scope of these is  krakjoe/phpdbg#59 _and_ krakjoe/phpdbg#69.  Sorry about that, but I had to include the first to implement the second.

Also note that this branch is a few commits behind krakjoe/phpdbg/master so you'll need to merge these changes.  There's also a could of TODOs outstanding as discussed in krakjoe/phpdbg#69.