avoiding the NPE if there is no default command in a group
adding optional discussion and example section at the end of the usage output for a command, fix #8
removed the trim from the table printer in an earlier commit, which broke a couple tests.  but we dont want to trim in some cases for pre-formatted examples, so it seems like the middle ground is only trim from the end of the string rather than both sides, tests pass ane examples are formatted correctly
small fix for default command parsing to avoid errors when they're used in certain cases
another minor adjustment to default command handling for the default application command, tests for examples & discussion stuff, test for default command
merging in 2795807