Add PT Serif to the repo

[ekohilas]

PT Serif is not included in the repo, causing different operating systems to output different font to the generated images.

Include the font within the repository and optionally create a reference to avoid having to install it.

[ekohilas]

Updated to use PT Serif as that is what it seems the game is using.

Not sure if bold or not.

[That-Guy977]

I've found references to the font files LCDPHONE, PerfectDOSVGA437, LiberationSans, PTF75F (which seems to be the file name for PT Serif Bold), PTSerif-Bold, Arial. Of these, PTSerif-Bold/PTF75F is the only serif font, so seems like it's that. A visual check also confirms that it's that, compared to the regular weight.

Checking the files, seems like the PTSerif-Bold font is heavier than PTF75F, but a font site lists them as the same entry. Not sure what's up with that.

[ekohilas]

That's an interesting note. It might just be that the font looks heavier with a larger size, but then might look the same at a smaller size.
I'll give it a try when I regenerate the files.