Alright, with the Mesa software solution, I have OpenGL2.1 with 5fps on
the Atom N450 netbook (GMA3150, 1024x600px), and -errm..- 2.6fps on an
"illuminated" landscape. Graphic quality is good, no artifacts, fonts are
perfect. This is the first time I see Stellarium 0.13/Qt5.2 on this
platform! I hope "full-size" PCs with similarly outdated OpenGL1.4-only
Intel GMA can achieve higher frame rates. For the netbook I may want to
keep using 0.12.4. Maybe some new things can be backported to a final
old-hardware version, 0.12.5?
Another observation: night mode seems not to do much atm.