adds readme

Signed-off-by: mrzl <lzrm@mrzl.net>
- now passing a buffer to the draw function
- removes global buffer object

Signed-off-by: mrzl <lzrm@mrzl.net>
- implements function to export a pdf of the lines. - not yet working

Signed-off-by: mrzl <lzrm@mrzl.net>