pcb-rnd 2.0.0
~~~~~~~~~~~~~

The major version number bump has two reasons:
 - The old data model got fully removed; from version 2.0.0, internally
   pcb-rnd speaks only the new, clean data model and export plugins
   translates forth and back when loading/saving in legacy file formats.
   This completes an 1.5 years long effort to get rid of legacy and
   limitations imposed by decades old design decisions.
 - The new, better organized, more new-user-friendly menu and hotkey system;
   the menu is now the same for lesstif and gtk and it features context
   popup menu that depends on object type under the mouse cursor. The default
   mouse button binding is less strange: popup menu on right click.

The grid size and offset system got rewritten too. Instead of hardwired
settings in the menu file, the user can specify a list of grid sizes, units
and offsets in the config. Being in the config, this allows per user, per
project or even per board file preferences.

Among with the old data model, the old, local rtree implementation got
removed too, in favor of genrtree.

There was a major upgrade on plugins too:
 - the xy exporter got user configurable templates, so it is now possible
   to define new export file formats (even user or project or board file
   specific ways) with editing configuration only
 - the ipcd356 plugin got rewritten for the new data model
 - a new ipcd356 import plugin is available

Finally, extensive automated and manual testing resulted in collecting
a long list of bugs. In turn most of the development cycle was spent on
fixing bugs.