* Revert preservation of input file modification times in output files,

* Revert preservation of input file modification times in output files,
  since this leads to too many problems with web caching, especially with
  inlined pages. Properly solving this would involve tracking every page
  that contributes to a page's content and using the youngest of them all,
  as well as special cases for things like the version plugin, and it's just
  too complex to do.