Extend drawing API to draw more shapes

[SunnieShine]

The goal is to allow APIs drawing more shapes onto a sudoku image, even variant sudoku elements such as diagonals, dots, comparison signs and so on.

Note
This issue may list some members that they are not appeared in standard sudoku rules, but they will be really useful on drawing, so I will plan to support them in API.

Gallery

• Embedded
  • Single cell
    • [Drawing] Neighbor Sign #365
    • [Drawing] Wheel #366
    • [Drawing] Pencilmark #367
    • [Drawing] Triangle Sum #368 (Triangles & Rectangle)
    • [Drawing] Star Product Star #369
    • [Drawing] Arrow #370
    • [Drawing] Average Bar #378
    • Corner mark
      • [Drawing] Cell-Scoped Triangle #377 (for diagonal-touched directions)
      • [Drawing] Cell-Scoped Arrow #379 (for all surrounding directions)
      • [Drawing] Cell-Scoped Skyscraper Arrow #381 (for adjacent directions)
    • Other shapes
      • [Drawing] Cell Shapes: Triangle #371
      • [Drawing] Cell Shapes: Square #372
      • [Drawing] Cell Shapes: Circle #373
      • [Drawing] Cell Shapes: Diamond #374
      • [Drawing] Cell Shapes: Star #375
      • [Drawing] Cell Shapes: Heart #380
  • Adjacent cell
    • [Drawing] Consecutive Bar #357
    • [Drawing] Kropki Dot #358
    • [Drawing] Greater-than Sign #359
    • [Drawing] XV Mark #360
    • [Drawing] Number Label #361
  • 2x2 square cell
    • [Drawing] Battenburg #362
    • [Drawing] Quadruple #363
    • [Drawing] Clockface Dot #364 (White dots for clockwise and black dots for counterclockwise)
    • [Drawing] Quadruple Max Arrow #376
• Outside
  • [Drawing] Skyscrapers #392
  • [Drawing] Answer Line Marks (A, B, C, etc.) #393
• Grouped
  • [Drawing] Diagonal Line #383
  • [Drawing] Capsule #386
  • [Drawing] Pyramid #387
  • [Drawing] Hypersudoku Window #388
  • [Drawing] Oblique Line (45n-Degree Slope) #389
  • [Drawing] Oblique Line (Non-45n-Degree Slope) #390
  • [Drawing] Lever #391
  • Killer Cage
  • Arrow
  • Thermometer
• [To be added]

[SunnieShine]

This issue is nearly completed. I'll close it and then implement last items with my pace.