Make use of the axes "ticklabelinterpreter" property (bug #45438) * plot.txi: add an anchor pointing to usage of interpreter property * genpropdoc.m: document axes "ticklabelinterpreter" property and text "interpreter" property * gl-render.h: new private attribute "interpreter" that stores the interperter to be used in text_to_pixels * gl-render.h (set_interpreter): new protected virtual method to set "interpreter" * gl-render.cc (opengl_renderer::draw_axes): set interpreter before rendering tick labels * gl-render.cc (opengl_renderer::text_to_pixels): make use of interpreter attribute * graphics.cc (axes::properties::set_defaults): initialize "ticklabelinterpreter" instead of unused "interpreter" * graphics.in.h (axes::properties): fix doubly defined defaults for "ticklabelinterpreter" and "interpreter" properties

--- a/libinterp/corefcn/graphics.cc	Thu Jun 25 08:32:21 2015 -0400
+++ b/libinterp/corefcn/graphics.cc	Tue Jun 23 22:21:50 2015 +0200
@@ -5056,7 +5056,7 @@
   yticklabelmode = "auto";
   zticklabelmode = "auto";
 
-  interpreter = "none";
+  ticklabelinterpreter = "tex";
 
   color = color_values ("white");
   xcolor = color_values ("black");