[RFC] New feature: --batch to accept command sequences from stdin (or file)

[Jari Aalto+mail.perl]

bzr startup time, as for all interpreted languages (Perl, Python ...)
is quite constly. Especially under Win32/Cygwin it takes 3-5 seconds
before simple "bzr ci" is run under old hardware.

Running series of command is therefore quite time consuming under some
OSs/hardware.

It would be nice if bzr somehow accepted commands to run from 
stdin, from file or command line. Something like:

    brz --batch "bzr init; bzr pull ../devel; ..."

Or:

    echo "bzr init; bzr pull ../devel; ..." | bzr --batch

Or: 

    brz --batch-file commands.txt

The commands would be started with word

    bzr ...

just like in command line and terminated with semicolon

    ;

The --batch option would be only one allowed perhaps along with
--verbose to display each command prior execution.

This would be nice feature for future releases.

Jari