Make lab exercises better

[maplant]

• Try going through the labs. Write down any problems noticed.
• Fix said problems.
• Particular ideas:
  • Create more in-depth lab for version control
  • ...and code profiling
  • ...and using the shell well
  • ...and for using good diff/merge tools
  • ...and for customizing dot files.
• There were some issues with the grep lab. For example, people don't have to use lookarounds on the problem to test lookarounds. Exactly how the phone numbers thing is supposed to work is unintuitive to a lot of people.