Multiplot margins and spacing options 5.0-branch vs 5.1

[Christoph B. <us...@be...>]

Hi Ethan,

I had submitted a patch to update and fix the behavior of multiplot's 
margins and spacing option, http://sourceforge.net/p/gnuplot/patches/713/

You had improved the patch, so that

* the default units are `screen`, and not `char` (as I had):
* the ordering of <top> and <bottom> doesn't matter and is swapped 
internally if required.

Seems, like you committed your updated patch only to CVS, but applied my 
old patch to the 5.0 branch.

Check the following script, which behaves as expected with 5.1 CVS, but 
not with the stable branch. All three plots should be identical:

set multiplot layout 2,2 \
     margins screen 0.1,0.9,0.9,0.1 spacing screen 0.1 \
     title 'Margins order <top>,<bottom>'
do for [i=1:4] {plot i*x }
unset multiplot
pause -1

set multiplot layout 2,2 \
     margins screen 0.1,0.9,0.1,0.9 spacing screen 0.1 \
     title 'Margins order <bottom>, <top>'
do for [i=1:4] {plot i*x }
unset multiplot
pause -1

set multiplot layout 2,2 \
     margins 0.1,0.9,0.1,0.9 spacing 0.1 \
     title 'No explicit units, should default to "screen"'
do for [i=1:4] {plot i*x }
unset multiplot

Thank you,
Christoph