Update DustMite

Commits:
* 1f0a0cd dustmite: Fix deprecated use of canFind
* 1035b15 dustmite: Improve progress indicator accuracy
* 556a9ab dsplit: Avoid stack overflow with very long lists
* 6b8f49c Avoid std.string.startsWith, which does pointless UTF-8 decoding
* 8eb5282 dsplit: Don't parse DDoc files as D source
* 403ef2f dsplit: Fix possible range violations in skipSymbol