Add 2nd newline to some Contents.m files and others.

Octave 3.7 has trouble locating some top level help files, aka
Contents.m files if they don't end in 2 blank lines at the end.
Bug? Feature? Who knows?
PsychImaging: Simplify use for non-task case and error case.

* Allow 'PrepareConfiguration' to be called when a previous
  configuration phase hasn't ended yet, e.g., due to some
  error during PsychImaging('openwindow'), the most trivial
  case being a sync failure at openwindow time.

  Output a warning and just restart configuration phase, instead
  of error abort.

  -> Should make this most common case easier to handle.

* Allow call of 'OpenWindow' without a previous 'PrepareConfiguration'.
  Call 'PrepareConfiguration' implicitely if not called before openwindow.

  This allows to use PsychImaging('OpenWindow', ...); as a drop in
  replacement for Screen('OpenWindow', ...); without need for a
  PsychImaging('PrepareConfiguration') first. Called this way, it will
  mostly behave like a regular Screen('openwindow') call, without
  processing any task specs.

  -> Encourages use of PsychImaging('OpenWindow') instead of Screen('OpenWindow')
     in future scripts, so users get in the habit of taking advantage of it and
     less explanation for the replacement procedure is needed.

* Make PsychImaging subfunction name matching case-insensitive via strcmpi().
Screen('ColorRange'): Optionally apply [0-maxvalue] to Screen('MakeTexture');

Screen('ColorRange') or PsychImaging('NormalizedHighResColorRange'); now
optionally accept a new flag 'alsoApplyToMakeTexture'. If set to 1, then
Screen('MakeTexture') will apply the colorRange setting also for standard
low precision 8-Bit integer textures if the input image matrix is provided
in double precision format instead of uint8, ie., as typically created by
Matlab/Octave matrix operations. This is achieved by scaling the double
input values properly before casting to uint8. Of course range limit to
[0; maxvalue] still applies, and standard textures are still limited to
8 bit or 256 levels.

-> This makes behaviour for standard precision 8-Bit textures consistent
   with behaviour of other Screen() drawing commands if a non-standard
   colorRange is selected. Especially useful for a normalized [0.0; 1.0]
   range, for specifying stimuli in a device independent normalized intensity
   range.

-> Opt-In: Not enabled by default to retain backwards compatibility.

-> Screen for 64-Bit Octave on Linux rebuilt and tested.