slightly better default sizing of drawings

Dependencies

• [2] JVRL5TWL store device-independent coordinates inside drawings
• [3] WDWXNW7V slightly strange way to move points
• [4] JCSLDGAH beginnings of support for multiple shapes
• [5] 2C7CTIQY make space for multiple kinds of width
• [6] FJ4L6N74 draw lines by default
• [7] IZZVOCLB confirm that we have access to all of the love API
• [*] OTIBCAUJ love2d scaffold
• [*] 2KRK3OBV don't rely on defaults

Change contents

• replacement in main.lua at line 41
  [2.142]→[2.142:168](∅→∅)
  − drawingw = 400 -- pixels
  [2.142]

  [2.168]
  + drawingw = nil -- pixels
• edit in main.lua at line 68
  [10.75]

  [9.183]
  + drawingw = math.floor(screenh/2/40)*40