Make hv curves and tangents also respect the new handle size setting.

Also a new preference InactiveHandleAlpha which lets you set the alpha
value for inactive handles on the glyph view. Default is fully opaque (255),
setting it to 55 makes the inactive handles less harsh.

open paths have all their handles drawn fully opaque.
Merge pull request #627 from monkeyiq/2013july/largesizeotherpoints

Make hv curves and tangents also respect the new handle size setting.