#200 alignment of vertical axis labels wrong for wxwidgets (new driver)

[giloo]

This is only when using the Hershey font: drvopt "hrshsym=1,text=0"
Easy to reproduce:
examples/c++/x29 -drvopt "hrshsym=1,text=0" (select 7, wxwidgets) -> wrong Y axis
examples/c++/x29 -drvopt "hrshsym=1,text=1" (select 7, wxwidgets) -> good Y axis