User capabilities issues with admin links, post type UI

[jmdodd]

In Dashboard view, Forums, Topics, and Replies custom post type UIs are not available, preventing the creation of forums.

When there is a forum, in a single topic view, topic and reply admin links are not present even for admin user with all capabilities.

Tested under r4332, but existed prior.

This issue only presents itself on new installations when the user activating bbPress does not have the Key Master role. A quick workaround is to automatically set the user that activated the plugin as a Key Master, which makes sense given the context.

(In [4335]) Capabilities:

• Introduce bbp_get_user_role_map() to more intelligently map WordPress roles to bbPress roles.
• Use bbp_get_user_role_map() in bbp_set_current_user_default_role().
• See #1939.
• Fixes #2010.

(In [4341]) Capabilities:

• Add tool for remapping site users to the expected forums role.
• Does not remove existing WordPress core roles.
• See #1939, #2010.