Updates on version 4 (likely final)

I'm not sure how many people update new versions, but I'm not suspecting many so I don't plan on making many more edits (besides this version is pretty complete).

At the end of the exponentiation section a "Tips" guide is given.
In the Chinese Remainder Theorem section problems 10,12, 13 were added.
In the diophantine equations section problems 18 and 19 were added.
The order section is now complete.
Example 35 was added in the miscellaneous section.
USA TST 2003 and exponential diophantine equations were added in the challenge section.
The problems version has been fully updated along with hints.

Things we request of the readers

Seeing as the majority of the sections seem "complete" to me in terms of the number of problems we likely won't be adding much more to the document. I'd say the exponentation, order, chinese remainder theorem, and challenge problem sections are all complete. If there are very nice construction or diophantine equations please private message me. Besides for this, unless there is a problem that I'm like "djmathman this problem is so awesome we have to include it" we won't be adding any more problems.
Please point out any typo's in the document.

Thanks guys for your support and I hope you enjoy the final version of our document!