Essentially a port of WP Internal Pointers for Stream. Needs work to allow extensions to hook into it.
Modified to allow other extensions to more easily add their own admin pointers through this class.
Merge remote-tracking branch 'origin/develop' into issue-466
Fixed phpcs errors.
Implemented 'load' setup method, also added missing braces and switched escaping to JSON encoding.
Removed superfluous quotes from JSON encoded output.
Now using proper constants for hooks
Merge branch 'develop' into issue-466
Some code formatting
Use constants for page slugs
Changing wording
Use constant for admin parent page
Merge pull request #479 from x-team/issue-466

Proposed solution to #466, adding support for admin pointers