convert sheet directly to bmp

[mjishnu]

The current version first convert the sheet to png before it is converted into bmp, this change allow to convert the sheet directly to bmp.

produces same output as current version

code changes made

img = Image.fromarray(cv2.cvtColor(image, cv2.COLOR_BGR2RGBA)).resize((100, 100))

overall changes

• changed file names
• moved parts of pngtobmp.py to sheettopng.py
• commented/removed unwanted code in pngtobmp.py

the massive number of additions/deletion are due to my formatter i apologize for that