Adds docstring example to system.fieldPairs.
Adds do notation example to algorithm.sort.
Avoids temporal string in tables hashing example.
Adds to tables module example of reference type vs value type.
Adds brief intro to hashes module.
Documents -d: in the compiler guide and hyperlinks assert/defined.
Revert "Adds to tables module example of reference type vs value type."

This reverts commit bde9d1ac0753e46c726dc63930539bb82d09f19d.
Merge pull request #1251 from gradha/pr_misc_docs

Misc docs suggestions