Add a new .piq-alias property for field and options

Just recompile the self-spec from the latest piqi version.
Add a new record-level .piq-positional property

When specified, it applies to all record fields unless overridden by a
per-field setting.
Fix a crash in piqic-erlang

it was crashing trying to ++ malformed lists
Merge remote-tracking branch 'alavrik/master' into spil