International fonts improvements: better sizing properties, better IME support on Win

[DP News-Robot]

Our demo examples/fonts/test_local_characters was improved a lot. It’s now both simpler and more powerful, shows the advised approaches: just set up TCastleFont to load fonts from TTF/OTF and assign it to (like TCastleLabel.CustomFont) or . See manual about text and fonts. With big thanks to Freedomax, our now works with Windows IME much better. The …