Include file relative to processed markdown file

[kamar535]

It would be great if there was an option to include a file relative to the markdown file being processed.

For example if we have the following directory structure.

.
├── a.md
└── sub
    ├── b.md
    └── c.md

To include c.md from b.md someting simlar to {!./c.md!} could be used. To include a.md from b.md something similar to {!../a.md!} could be used.