Replace existing images with text on them with actual text drawing

[AlexKhayrullin]

In order to make the game possible to fully localize, some pictures need to be replaced with uses of draw_text with appropriate fonts:

• "Yes", "No", "No Save", "Past", "Future" and other strings on the save selection screen.
• Metal Sonic's lines (also, make use of the opportunity to make the text appear letter by letter like in an RPG textbox, that might be a nice visual effect)
• ... others? The two examples above are the most prominent ones, but there might be more.

[AlexKhayrullin]

Replaced the Metal Sonic lines. @nkrapivin has done the rest. The present/past signposts are covered in #80 .

So that's all of them.

[AlexKhayrullin]

Reopening because one sprite still remains: the "Game Over" label.

Might as well use the opportunity to implement (and make translatable) a "Time Over" message #94

[nkrapivin]

string_upper only works with A-Z letters afaik: https://docs.yoyogames.com/source/dadiospice/002_reference/strings/string_upper.html

[AlexKhayrullin]

It worked with Russian letters too, but good point, I'd better remove string_upper and just make the strings uppercase to begin with.