Replace nonfree fonts

[akien-mga]

The two fonts currently used by Jetpaca are nonfree as per https://github.com/KOBUGE-Games/jetpaca/blob/master/README.md#fonts

We should find replacements for the first open source release.

[akien-mga]

For the reference, in #4 (comment) @punto- said that he saw those two fonts:

• ArmWrestler.ttf
• BPdiet.otf

With a closer look I don't see what ArmWrestler.ttf would apply too in current Jetpaca, but that might have been the invalid and unused font_big.xres.

BPdiet does look like our "TAP TO FLY" and "WORLD 1" texts:



There are small differences but the BPdiet website says that the font was updated in 2018, which might explain them.

The HUD and in-game texts seemed to use the Aller Bold font from what I can find with image search.

I'm about to replace it with Mozilla's Fira Sans Bold, which looks quite similar (not so much for numbers though):

If we find Bold too bold, we could also go with Fira Sans SemiBold.

[ObaniGemini]

Are there still fonts to be replaced or can this be closed ?

[akien-mga]

"WORLD 1" and "TAP TO FLY" images are still derived from a nonfree font.

Not sure about the Jetpaca logo itself, but it looks like it might have been drawn by one of the Jetpaca artists.