Textbook: thoughts for next-time

[bartsnapp]

• Are the problems in the correct order? E.g. 1.3 needs to be
  re-ordered, in particular, 6 is too hard too early. MARKED
• break limits into two chapter (just uncomment the chapter in
  infinity and cont)
• Add "tolerance" word problems to limits section (2.2 I think) see
  section 2.5 of Finney Thomas Demana Waits.
• Do we really want to do the chain rule before derivatives of trig?
• Add curve sketching in "Basics of Derivatives" this can be done
  through tables etc.
• Place derivative of e^x in the next chapter (Derivative of e^x,
  Product Rule and Quotient Rule)