Add support for base menu directory

Add support for a base menu directory so that default menu filename and
role-based menu filenames may be specified as either full pathnames or
relative pathnames (relative to the base menu directory).  Update sample
configuration files accordingly.

Add notes in README.txt and INSTALL.txt that Ramp requires PHP 5.3.
This was not true originally, and was tested at some point with
5.2.something, but Ramp now frequently uses the variation on the
ternary operator, new in 5.3, which allows the middle section to be left
out.

Improve description of Report activity in rampDemo/index.act.
Add support for session timeout

Add support for a session timeout, without the timeout reset every time
the user goes to a new screen.  Update sample configuration files
accordingly.
Support continuing to attempted dest. after login

Support continuing to attempted destination (e.g., unauthorized table)
after being asked to login (and possibly set password).