[doc,system] Fix up more date documentation.
[doc,system] Link up table of date/duration ops.
Improved "Methods & Generic Functions" intro doc.
Merge pull request #582 from BarAgent/docs

Improved "Methods & Generic Functions" intro doc.
[doc,duim] Update year in copyright notice
[doc,duim] Improve cross linking in conventions
[doc,duim] Improve geometry module

- Fix the formatting of 3 functions
- Improve cross linking
[doc,duim] Improve extended geometry library
[doc,duim] Convert DCs library to the new format
[doc,duim] Convert Sheets module to the new format
[doc,duim] Use tables for class hierarchy
[doc,library] Start cleaning up numbers.
[doc,duim] Fix indenting to unbreak build.
[doc,duim] Remove layout shim images.

Also, fix captions as we go.
[doc,library] Fix typo.
[doc,library] Fix indentation.
[doc,library] Start adding SQL documentation.
[sql] Fix some typos.
[doc,library] More SQL library docs.
Fix typos.