Glyph Support Request: U+2295 CIRCLED PLUS / U+2297 CIRCLED TIMES / U+208B SUBSCRIPT MINUS

In order to use this font for drawing diagrams of digital circuits, it would be great if you could add support for some glyphs:

| Codepoint | Usage |
| ------------------------ | ------------------------------- |
| `U+2295 CIRCLED PLUS` | XOR gate |
| `U+2297 CIRCLED TIMES` | AND gate |
| `U+208B SUBSCRIPT MINUS` | Indices (in this case for bits) |

## Example: LFSR diagram

### Vim (using Fira Code)


### Rustdoc (using Source code Pro)

### Plain text version

This may also look broken depending on your browser font:

```
MSB LSB
┌─────┐ ┌───┐ ┌───┐ ┌───┐ ┌───┐
┌──▶│ sₐ₋₁├┬──▶ ... ─▶│ s₃├┬▶│ s₂├┬▶│ s₁├┬▶│ s₀├┬───▶ output bit
│ └─────┘│ └───┘│ └───┘│ └───┘│ └───┘│
│ ▼ ▼ ▼ ▼ ▼
│sₐ ⊗ ◀─pₐ₋₁ ⊗ ◀─p₃ ⊗ ◀─p₂ ⊗ ◀─p₁ ⊗ ◀─p₀
│ │ │ │ │ │
│ ▼ ▼ ▼ ▼ │
└─────────╴⊕ ◀─ ... ◀──────⊕ ◀────⊕ ◀────⊕ ◀────┘
```