add already implemented links to WP-Spec
add already implemented links to Project-Spec
add already implemented property to User-Spec
add specification for existing Status-Endpoint
condense introduction

- use fewer groups (making sidebar navigation in rendered Specification
more useful)
- remove redundant error object chapter
add specification for existing Priorities-Endpoint
add specification for existing Categories-Endpoint
add specification for existing Versions-Endpoint
add compatibility disclaimer to intro
Merge remote-tracking branch 'origin/dev' into fix/get_apiv3_spec_uptodate

Conflicts:
	doc/apiv3-documentation.apib
add already implemented links to WP-Spec
more precise type-spec
fix table
isStarred is only changable via another endpoint
update Spec to match Implementation

PATCH is also more apropriate, because we only change (and specify) the
comment, nothing else...
Add some words about Authentication
specify error codes for PATCH operations
temporarily disable PATCH for workpackages

- should be currently unused
- contains critical security flaws that should not make it into OP 4.0
add "not implemented" marker to another endpoint
replace tabs by spaces