#10 New \'walk\' mode for test playback

[sdemi]

This patch adds the ability to playback tests in 'walk'
mode by setting the marathon.playback.walk property to
"true". Setting the property to "true" causes a 1
second delay to occur before each Marathon action in
the script is executed, allowing the user to watch the
test execution steps. This is mainly useful for
debugging test failures.

This patch is dependent on (includes code changes for)
the patches for assertForegroundColor and
assertLineBorderColor.

The following changes were made to the code:

An __init__ method was added to the Marathon class in
playback.py to set the value of the _delay variable,
which is defined in Marathon.java.

[sdemi]

libpy.marathon.playback.py