V3

[simonhaenisch]

Changes:

• Requires at least Node 10
• Convert to Typescript
• Expose --port CLI flag
• Change license to MIT
• use stdio to read from stdin and maybe output to stdout (will add later)
• allow shell globbing to input multiple files from different directories (breaking change)
• ensure correctness of relative paths (Stylesheet paths are not relative to the file they are in #37 (comment))
• auto-set displayHeaderFooter if either a header template or footer template is set

Closes #22.
Closes #23.
Closes #28.
Closes #34.
Fixes #36.
Fixes #37.

[karlhorky]

Nice one @simonhaenisch, cheers for this!