Add more example notebooks

[cberys]

Wishlist:

• turning exchange CTDs into text for read_exchange with file separator
  • cat into a sincle file
  • ! for sed so there is no discontinuity
  • read back into hydro
  • comments (!!!)
• aliasing params
  • ALT_1 how the flags and error etc columns work
• maybe second remove and add columns which is more verbose