modulefile man page is currently in the section 4 of man. According to
"man man", this is incorrect, as section 4 is for "Special files (usually
found in /dev)". The man page for modulefile should be in section 5,
"File formats and conventions, e.g. /etc/passwd".
This patch moves modulefile(4) to modulefile(5).
Fixes#518
Modernize and simplify modulefile code examples in documentation:
* Follow coding convention defined for the project
* Use simple "#%Module" file signature, no "1.0" suffix needed
