Trivial: install script should now work on Mac, too.
Make Dontprint an XPCOM service

Make an XPCOM service "@robamler.github.com/dontprint;1". This is
roughply Mozilla's concept of a singleton.

  * The core functionality will now only be loaded once on Firefox
    startup instead of once for every browser window.

  * Browser-window specific code is now in new object "DontprintBrowser".

  * Code from other files (such as opened tabs, options window,
    post translators) now connects to Dontprint using Component
    .classes['...'].getService() instead of having Dontprint set
    up a connection to the external code. Tabs that need additional
    data get an ID as their hash tag. After receiving a reference
    to Dontprint, they use this hash tag to receive the additional
    information from Dontprint.
Undo commit f8dd50f6

It seems like commit f8dd50f6 was wrong. It only partially
worked around a problem that came from initializing a
separate Dontprint object on each browser window. Since we're
no longer doing that, we no longer need this workaround.
New database schema

Use a new layout of database tables. The new schema allows for more specific
filters (most importantly: minDate and maxDate). It also allows to set
specific k2pdfopt command line parameters on a per-journal level and it
defines precedence of conflicting filters and makes it possible to
overwrite built-in filters in a well-defined way both by the user
and by updates.

This commit includes
  * Creation of the SQL tables.
  * Port of pdfcrop (including revised UI)
  * Port from inches to mm

The following is separated into the next commits:
  * Port of convertDocument()
  * Port of reportjournalSettings()
  * Implementation of a new tab on the options window
    that allows to edit the journal settings
  * Implementation of privacy settings (neverRoportJournalSettings)
Port convertDocument() to new schema
Port reportJournalSettings() to new schema
Add "margins" tab to options window.

The new tab allows the user to fine-tune journal settings. Both custom
and built-in journal settings can be changed or deleted.
Implement privacy options (neverReportJournalSettings)
Implement functionality to dontprint local files.

Add a menu item "Tools --> Dontprint --> Send a local PDF document
to e-reader". When selected, Dontprint displays a file picker and
runs a job of the new jobType "localfile" for each picked file.

TODO:

  * Promote this functionality in add-on description, on welcome
    page and on website.

  * Make the progress page a drop target for local PDF files.