ESP8266, NodeMCU: how to create xbm images for displaying on OLED 128×64 I2C Displays

Do you know these wonderfully cheap SSD1306 based OLED displays with the crispy display? For a while now the NodeMCU Lua firmware for the ESP8266 supports them and has a rich feature set to draw lines, circles and even bitmaps. One way to draw bitmaps is in the XBM format, which is originally a text based format and they can be directly included into C code: #define clouds_width 60 #define clouds_height 60 static.....