sumtype: Use non-packaged import for std.format ...

std.format was split into modules in v2.097, but we want to be compatible
with older versions of the frontend, so use the package as a whole.

sumtype/dyaml: Work around various compatibility issues with v2.097

Add configy library, dyaml, tinyendian ...

Versions are:
- tinyendian v0.2.0
- dyaml v0.9.0
- Configy commit 361ca47 + PR34

vendor