Use a DynamicFont for the default project theme

This makes font oversampling work out of the box, while also increasing
the supported character set's size. The default font is now larger
as well to better fit today's screen resolutions.

The OpenSans SemiBold font was chosen for two reasons:

- Small file size, yet its character set supports Latin-1 and Cyrillic
  text.
- A heavier font weight looks better in most "game" scenarios and is
  more readable against mixed-color backgrounds.

This is considered a breaking change as it changes the default font's
metrics, which will likely affect how Control nodes are laid out in
scenes (unless a custom font is in use).

editor/editor_builders.py

@@ -53,7 +53,7 @@ def make_fonts_header(target, source, env):
     g.write("#ifndef _EDITOR_FONTS_H\n")
     g.write("#define _EDITOR_FONTS_H\n")
 
-    # saving uncompressed, since freetype will reference from memory pointer
+    # Saving uncompressed, since FreeType will reference from memory pointer.
     for i in range(len(source)):
         with open(source[i], "rb") as f:
             buf = f.read()