This allow safe caching of the pages by the browser and still display the right
amount of elapsed time upon page refresh.
If javascript is disabled, absolute time is displayed, leaving it readable.
All the templates have been updated.
Remove the `install_package_data' subclass of `install_data' and use
the `package_data' functionality provided by distutils instead. As
package data must be located within the package directory, the data
files are now generated in the build directory.
To simplify the functionality of this change, the top-level `doc' and
`templates' directories have been moved into the `mercurial' package
directory.
