#1 Upload/download functionality

[Martin Geisler]

PHP Shell should provide an internal upload and
download functionality.

The download functionality could be implemented with a
new internal command called something like 'download'
which takes a filename as argument and, well...,
downloads the file.

The upload functionality would be of the standard
<input type="file"> type, maybe with a checkbox to
confirm overwriting other files. This could be
configurable.