patch: qtterminal: make point plots aware of linewidth

[Dieter R. <die...@ps...>]

Hi everybody,

this is my first contribution here, so if my form or the way to send 
this patch is wrong, please correct me.

-----------------

The qt terminal did not take the linewidth parameter of a plot into 
account, when plotting 'with points'. Especially for point types 1 and 
2, but in general for all non-filled point types, this results in points 
drawn with very thin lines, which tend not to be visible well when 
printed, for example.

Attached patches change this for gnuplot 4.6.5 and latest 4.7-CVS.
Like on other terminals, it's now possible to plot 'with points lw 2' to 
get the points made of thicker lines.

I am not sure, if the way I implemented this is the right way, 
especially for the more complicated QtGnuplotPoints:: way of drawing points.



Thanks in advance for feedback on these patches.

Cheers,
Dieter