Text Filter macro

This macro implements "text filter" functionality. The selected text in the
current buffer (or the entire buffer if no text is selected) will be passed to
stdIn for the command specified by the "osCmd" parameter. The originally selected
text (or the entire buffer if no text is selected) will be replaced by the output of
the command.

USE AT YOUR OWN RISK

Include this macro in another macro using the #include directive.
Form an command to call and pass it the TextFilter proceedure as shown in the following
example:

#include ".\TextFilter.vbee"

osCmd = "java -cp ""path\to\some.jar"" someclass"
TextFilter osCmd