- Tidied up clean target variables to eliminate redundant double-deleting.

- Corrected clean file lists to cater for PNG files in the print version.

- Generalised content path processing so that content files may be placed ...

anywhere within the paper directory tree.

- Added install targets. ...

- Now includes paper variables include file.
- Added conditionals to clean targets to check whether the "clean lists"
  are empty.

- Added include and template files for new handbook infrastructure.