Text antialiasing bug

[v0dro]

A weird problem happens when calling Figure#write twice on the same graph. For the first time, all the text on the Figure is antialiased however the second time, the text appears fuzzy and is probably not so.

Here is the image of the first time:

And this is the second time:

You can reproduce this issue by running any test in the rspec and comparing both images.

[v0dro]

@arzoo14 this might be a good opportunity for you to understand image magick.