Add --font-size flag

[mateosss]

After #18 is resolved, a --font-size or -s flag is needed for generating the pf2 file based not only in the correct font, but also with the correct size.

In the future this flag will be used for making the theme adaptable to different screen resolutions.

[4ndrej]

blocked by ongoing pull request #23

[mateosss]

However, if anyone wants to try to solve #18 it is more than welcome!

[4ndrej]

it seems that pull #23 waiting there is about #18

[mateosss]

Indeed, but it is still a work in progress, it needs to be updated based on its comments.

[4ndrej]

oh, I see

[mateosss]

After the python update, the --fontsize/-fs flag is now available in matter.py