[Bug-apl] Value constructors made protected

[Juergen Sauermann]

Hi,

in order to prevent the incorrect usage of constructors of class Value, I have made
them all "protected:".

This means that in your own code you should replace, e.g.:

Value_P Z(new Value(...));

by:

Value_P Z(...);

I.e. remove the words "new Value" and optionally the () that are now redundant.

I have adapted the libraries that ship with GNU APL (sql not tested) so please update your
repositories.

SVN 537.

/// Jürgen