New scripts:

- hotkeys, obdatacopier and renameobjectbyblock, all from Jean-Michel Soler (jms);
- bevel_center by Loic Berthe, suggested for inclusion by jms;
- doc_browser, by Daniel Dunbar (Zr)

  Thanks to them for the new contributions!

  (I included doc_browser at 'Misc' because only users interested in script writing would actually use it, but it could also be under 'Help'.  Opinions?)

BPython related:
- Added scriptlink methods to object, lamp, camera and world.
- Object: added object.makeTrack and object.clearTrack (old track method).
- sys: made sys.exists(path) return 0 for not found; 1 for file, 2 for dir and -1 for neither.
- doc updates and fixes.
- made ONLOAD event work.  G.f's SCENESCRIPT bit was being zeroed in set_app_data.
- Blender: updated functions Load and Save to support the builtin importers and exporters besides .blend (dxf, videoscape, vrml 1.0, stl, ...)
- Draw: added mouse wheel events.
- Scene: added scene.play to play back animations (like ALT+A and SHIFT+ALT+A).  Makes a good counter, too, when the 'win' attribute is set to a space that doesn't "animate".

The scene.play() addition and the fix to ONLOAD scriptlinks is part of the work for a Blender demo mode.  It already works, but I'll still add support for Radiosity calculations and fix a thing in main(): it executes onload scripts too early (BIF_Init), giving funny results in alt+a animations and renderings when firing up Blender.  Loading after the program is up has no such problems.  When I finish I'll post examples of demo mode scripts.