Refactored `ProcessorTask` into two specialized `ProcessorCommentTask`.

The original class will be the base for generic processor tasks dealing with all store objects, whereas the newly introduced comment task handles current batch of individual comment dealing tasks.
Added skeleton for merge known objects processor task.
Processor now invokes merge known objects task.
Processor now invokes link known objects task.
Implemented handling links to known adopted protocols.
Refactored `ClassInfo` to support links to super class.

Instead of simply storing name of super class as `NSString`, we now use `ObjectLinkInfo`.
Implemented linking to known super classes.
Added convenience property for accessing name of super class.
Refactored super class links detection into it's own method for better code clarity.
Implemented data structure for handling links to classes from categories.
Categories and extensions are now linked with the class they extend.
Merge branch 'link-known-objects' into experimental
Added skeleton fetch documentation task.
Refactored store objects and mocks creation for unit tests into common class and categories.
Implemented fetching documentation from adopted protocols.
Removed processor tests validating store objects get enumerated.

Enumeration by itself doesn't prove anything - it's what the code does on enumerated objects that counts... Besides, members enumeration tests started failing with latest stuff :)
Added link to parent interface from properties and methods.
Simplified unit tests for `LinkKnownObjectTasks`.
Implemented `--search-comments` cmd line switch for enabling or disabling searching for missing comments.
Merge branch 'fetch-documentation' into experimental