+ httpx: create another layer of Unmarshallers, FromBodyPartOptionUnmarshaller, to be able to unmarshal from BodyParts (including headers), refs #327
! http(x): create FormFile as an easy way to access uploaded file information for forms, fixes #327
+ http: simplify creating MultipartContent from a Map of FormFiles, fixes #327
= docs: add documentation for `clientIP`
= can: group commander dispatchs for easier instrumentation
Merge pull request #588 from ivantopo/easier-client-instrumentation

= can: group commander dispatchs for easier instrumentation
Merge pull request #585 from jrudolph/i/327/uploaded-filename

Various improvements for easier handling of file upload from forms, fixes #327
! routing: remove layer of `*Aux` classes by type aliases for simplicity
Merge pull request #590 from jrudolph/w/remove-one-FieldDefMagnetLayer

! routing: remove layer of `*Aux` classes by type aliases for simplicity
+ can: implement chunkless request streaming, refs #281
! testkit: move result.awaitResult call from `injectIntoRoute` into `check`, fixes #205
= can: also retry non-idempotent requests if connection attempt failed, fixes #532
= can: improve HttpManager extensibility by making child creation
overridable

Converts HttpManager's instantiations of `HttpClientSettingsGroup` and `HttpListener` to use the virtual class pattern, so it is easily overridable without having to duplicate the rest of the functionality in the class.
! routing: CompletionMagnet: gone, streamlining completion API: accomplished

This change comes from the insight that with the new marshalling
infrastructure in place CompletionMagnet doesn't serve any higher
purpose.

By removing the now useless magnet layer composition is reinstantiated and
unification as shown in the accompanying test works (with a little help
from type annotations)
= httpx: code reorganization to DRY up implementation of new ToResponseMarshallers
= io: fix garbling of big Tcp.Writes, fixes #601
Merge pull request #602 from jrudolph/i/601/big-write-problem

= io: fix garbling of big Tcp.Writes, fixes #601
Merge pull request #592 from jrudolph/i/281/chunkless-request-streaming

+ can: implement chunkless request streaming, refs #281
Merge pull request #596 from jrudolph/i/532/allow-retries-if-connection-attempts-fail

= can: also retry non-idempotent requests if connection attempt failed, fixes #532
Merge pull request #597 from jrudolph/w/streamline-future-marshalling

Streamline completing by replacing CompletionMagnet in favor of the more generic ToResponseMarshallable