minor fixes
seed: add `state` tool to explicitly save / restore currently running apps

Also improved `start` behaviour - if an app already has an endpoint that
differs from the running node, the new node will do a `ping` op and
take over the app iff the current endpoint doesn't respond in 5s.
added failing test for gzipping a large (>16kb) response string
seed: show app status as a muted version of running while starting
change order of mechanism execution to preorder, as this allows parent elements to establish a 'context' that child nodes can resolve in their mechanisms
Convert imports to alt namespace.
make surface/html module safe for use on server-side
work on docs
Add 'prepend' flag to surface::Mechanism
first cut at surface 'field context' implementation.
bootstrap form controls tieing into field contexts. wip.
fix field references.
'Error' not 'Errors'
make surface/bootstrap/components usable in nodejs hostenv
fix import
use new style stream primitives
make FieldMap and FieldArray purely structural containers; factor out Field interface
Make FieldArray automatically insert Fields for children.
fix map/array validation
Parametrize FieldArray template with index & array length observables