[ENH] MPEGPlayer-eToyVocabulary-dgd ( [er][et][sm][cd] works, improvements and fixes suggested )

[germanmorales at delta-sys.com]

suggested improvements and fixes:

MPEGFile>>convertToSqueakMovieFileNamed: doesn't seems to be part of
what this change set is for, and there are no senders in this change
set, I think it should be extracted.

MPEGMoviePlayerMorph>>guessVolumeSlider: uses "anObject class ==
SimpleSliderMorph"; it should use #isKindOf: to allow subclasses of
SimpleSliderMorph; finally, the test, perhaps, should be made against
Slider.

MPEGMoviePlayerMorph #getRepeat and #setRepeat have the wrong method
comment

the change set includes "Player removeSelector: #isRunning" and
"MPEGMoviePlayerMorph removeSelector: #isRunning": I can't find such
selector in my image, and I can't find any previous addition in this
change set.

reorganization of categories uses the category named
*Tools-FileList-accessing, which seems strange to me.

e-toy viewer: the up and down arrows to change the volume and position
increment/decrement the values by 1, but given that this values are
expressed in a 0 < x < 1 range, they force the values to 0 or 1 only,
which is undesired by the user.