fix aglio-warnings
specify expected format for PATCH endpoint
unify documentation of error responses
specify conflict cases
specify 403
improve example
specify error objects
sort and improve error id list
fix wp lines jump when hover over grouping
shrink intro on yet unspecified responses

also clarifying the meaning of collections
explicitly ban html from error messages
extend error specification

- allow collection of errors
- define ValidationError
remove definition of HTTP status codes

this list does not add more value than the standard definitions...
it is not even nearly the list of values our API will return by any
specification
change notation of multiple errors

embed them in a single error object to ease implementation of simple
clients, advanced clients wont care anyway
more clarification on embedded error infos
add HTTP 401 to MissingPermission identifier
be more precise about subject constraints
Test response for forbidden WP attributes
Check update attribute constraints
Test work package update for valid attributes