examples: Allow recent attoparsec, base
examples Wall: add type signature,

avoid name overlap
Move Serialize instances into STL.Types

To avoid orphan instances and satisfy -Wall
Wall: type signatures, extra imports, exports
Remove comma between vertices in text output

closes #3
bump version to 0.3
Changes for 0.3
cabal: fix lower bound of bytestring

we require `floatDec` for text output
examples cabal: require STL-0.3
examples: correct description of binary-roundtrip
nix: explicit versions of `cereal`, `bytestring`