Change: Rename some freetype things to fontcache.

The font cache supports more than just FreeType as a font provider, but still used freetype in some naming.

This now uses more suitable terms.

src/strings_func.h

@@ -273,7 +273,7 @@ public:
 	 * @param font_name The new font name.
 	 * @param os_data Opaque pointer to OS-specific data.
 	 */
-	virtual void SetFontNames(struct FreeTypeSettings *settings, const char *font_name, const void *os_data = nullptr) = 0;
+	virtual void SetFontNames(struct FontCacheSettings *settings, const char *font_name, const void *os_data = nullptr) = 0;
 
 	bool FindMissingGlyphs();
 };