Rewrite Post class
Rewrite Post class

Rewrite the entire Post class. Changes include:

- Add limits to query statements
- Change post_url to post
- Change page_number to range
- Add include guards
- Improve error messages
- Use globals for accessing Database and Utility classes
- Simplify methods
- Rename getLatest() to getBlocks()
- Index counters at zero instead of one

ecj2/kaku,ecj2/kaku