Simplify MediaWikiClient

For the user of the MediaWiki client, all of the internal errors are
basically I/O issues, so let's wrap the exceptions into an IOException
even if they weren't such exceptions before.

Signed-off-by: Johannes Schindelin <johannes.schindelin@gmx.de>
Prepare MediaWikiClient for more API functions

In the next few commits, we will add support for API functions we
introduced in the Fiji Wiki for the specific purpose of supporting
personal update sites better.

Signed-off-by: Johannes Schindelin <johannes.schindelin@gmx.de>
MediaWikiClient: add support for changing the upload password

This is required for better support of the personal update sites:
users should be able to initialize their own update sites from within
the updater's GUI.

Incidentally, this also adds support for logging in and out via the
MediaWiki API.

Signed-off-by: Johannes Schindelin <johannes.schindelin@gmx.de>
MediaWikiClient: add support for creating an Fiji Wiki account

This is required for better support of the personal update sites:
users should be able to initialize their own update sites from within
the updater's GUI: some people might not have a Fiji Wiki account
(because so far, we recommended creating such an account only for
people who actually wanted to be helpful and contribute something on
the Fiji Wiki).

There is a rudimentary security-by-obscurity measure in place to help
prevent flooding the Wiki with spammers' annoying and irritating
'content', but the idea is really to be light-weight on that side:
let's try harder to prevent such things only when we have to, and go
back to writing code for scientific image analysis in the meantime.

Signed-off-by: Johannes Schindelin <johannes.schindelin@gmx.de>
Updater (Swing): make it easy to initialize a personal update site

This change offers not only to initialize a personal update site given a
Fiji Wiki account and a password, but also to create a new Fiji Wiki
account (an email address is still required, and activating the account
using information sent to that email address, too, though).

Signed-off-by: Johannes Schindelin <johannes.schindelin@gmx.de>
wip

Signed-off-by: Johannes Schindelin <johannes.schindelin@gmx.de>