Reimplemented \include system for LaTeX.

A LaTeX package providing a backwards-compatible reimplementation of \include and \includeonly. The principal new features are:

• the restriction that \clearpages must surround an included file is removed,
• the restriction that \includes cannot be nested is removed, and
• the provision of hooks to be executed before and after the contents of an included file.
Newclude accomplishes the first two by using a single .aux file instead of many. Newclude also provides the experimental functionality of the unsupported package includex, which allows you to include partial contents of independent LaTeX files that can also be processed on their own (that is, files that contain \documentclass, \begin{document}, etc.).