Saves the image on the current back buffer to the file bmp$. This command is useful for screenshots.
The image will be saved as a 24-bit color image on all platforms.
Files can be saved in either bmp or png format. The file format is determined by the filename.
PRINT "Hello World", 100, 100
SAVEBMP "Test.bmp" // Save in bmp format
SAVEBMP "Test.png" // Save in png format