Truncate filenames according to (#33)

[lainq]

Hopefully fixes #33

Note: max_char_count can't be placed outside the loop since MeasureTextEx gives different values for different characters (can't form a constant value containing character width)

[rexim]

Tbh, I wanted to come up with a solution involving glScissors.

[lainq]

Oh, I'm not sure if I can do that with glScissor. I am not much familiar with the OpenGL api. But I'd really appreciate it if you could tell me about the solution.

Let me know if you want me to close this PR