wx.lib.plot.py - sub-title (another suggestion)

I like to have nice titles (no abbreviations if possible) on the plots,
but quickly run out of space.

Hopefully the enclosed patch providing an optional sub-title for plots
will be useful for others.

Please note that the patch is against 2.5.5.0rc1.

Best regards
Werner

plotSubTitle.patch (6.45 KB)