This commit adds some tables to help explain algebra.

This commit tries to start writing some documentation around
how the algebraic structures work and their relationship to
each other. It is very rough but hopefully moves us in the
right direction.
fix table formatting
continue fixing table formatting
Reorganize sections and add some more exploratory content.

Based on Oscar's comments, hopefully this will be a bit clearer.
Fix typo with distributivity law.
Fix more errors spotted by @posco.

I changed the "generic multiplication" operator to make it harder
for people like me to get it mixed up with "generic addition".

I also removed the assumption that idempotence commutes. I'm not
sure it's true: if it is, we can modify it again later.
Add section link
Fix links in README.
adjust links to point to the master branch
Merge pull request #16 from non/topic/basic-property-tables

Topic/basic property tables