This changes the previous behaviour of fetching always up to
500 most recent revisions.
Now the extensions fetches N revisions including the newer
revision selected to diff as the most recent revision.
N is number of revisions that would fit in the current
window when rendered as bars.
When user is close to either "end" of the slider, extensions
fetches another batch of up to N older or newer revisions,
as long as user does not reach the oldest or the newest
revision of the page.
Among others, this removes the limitations of the previous
approach: showing only 500 revisions, and failing to show
anything when any of selected revisions was older than
500 recent revisions.
This change also simplifies usage of Api class.
Bug: T135005
Change-Id: Ib3f4a6ac57ff17008f9d8784c4716bd294443096
After fetching a batch of revision data, user names are extracted
and another API query is made to get gender preferences for users.
This change also moves a code responsible for MediaWiki API calls
to its own class.
Bug: T136367
Change-Id: Id11fe14e9ca37829141ae92b13b51f10f992eb96
