Add More YMQ Tests

[magniloquency]

• The randomly drop packets test should be more reliable now, there's an upper bound on how many consecutive packets can be dropped for each peer
• The tests have better error messages when they fail now, also the macro was refactored to put most of the logic in a regular function as much as possible
• A few new tests suggested by @gxuu have been added

[gxuu]

Add a comment that gives the most common output string (for example file=stdout). This way if we run into problem and want to find out where the output is printed from we can grep the code.