By default,the create_font create a 8 bits/pixel fonts,but now it can be
transform into 4 bits/pixel and used on ESP8266/ESP32.I have tested it on
ESP32,both SPIFFS and flash array.
Main modifications :
1. add readInt16() and readInt8() functions;
2. add a flag c4bpp to struct gFont.
3. adjust 4bits mode display.
4. add a tool made by pure C to convert font files.
The API is compatible with previous.Compressed font format is described in
tools/create_smooth_font/compress_font/readme.md
Signed-off-by: Lucy2003 <53362310+Lucy2003@users.noreply.github.com>
Lucy2003