Made minor changes and fixed typos.

Next step: remove buggy "git init" intro and make it clear that
students must start from creating a repo in GitHub and then clone it.
Added section on creation of repo.
More on log and diff, including a table on HEAD and ^
Revert "More on log and diff, including a table on HEAD and ^"

This reverts commit 25e07bd69209fbcefe0e0ec0a4cb8e767e056018.
Once again, more on log and diff, including a table on HEAD and ^.
Several typos fixed.
Added a ref to the table of tag names.
Minor changes on conflict section.
Modifed the push/pull assuming that everybody pushes to/pulls from
origin, and that origin is the default value set by GitHub.

All the "git remote" material will be put as additional material.
Minor changes in the revert section.
Minor changes to exercises about Git.
Update from year 1 to year 2: new example on doubles, removed
references to groovy, etc.
Upgrade year 1 -> year 2.

Removed reference to for loop.

Added learning goals at the beginning.
Added notes on what to include as advance material.
Removed the EPS.
Modified plan for year 2.

I have been thinking about this (now is year 2, between D4 and D5 FT,
D2-D3 PT) and I think the solution to the connundrum

  - Trevor constraint, plus
  - Recursion contraint
  - Same content for both groups

is to break up the recursion days and have them apart instead of all
together. A bit of recursion at the beginning and then more recursion
later with the memoization and the divide-and-conquer; kind of like
"basic recursion" and "advanced recursion".
Starting D5-recursion1.tex.
Added a new (not very good) example.

Removed references to "static" from the first sections.
Moved memoization to the recursion2 day.
Added a small comment for clarity.