Construo 0.2.0

• Fixed id-overlap bug which caused construction to get corrput
  (wrong particles connected together)
• added zooming plus mouse-wheel support
• added scrolling with cursorkeys and mouse
• added simple GUI
• House of Horror Part1 and Part2 added (currently a bit broken due
  to changed physics)
• fullscreen support added
• moving of objects is possible
• rotation of objects is possible
• added optional glut support for hardware accelerated OpenGL
• support for anti-aliased lines and transparency (only under glut)
• fixed particle physics, particle mass now has an impact
• particle velocity editing is possible
• added file-manager with thumbnail preview
• added custom collider objects (aka boxes)
• moving of colliders in a running simulation is possible
• some bit more actions are undoable
• lots of new bugs and missing features, see file BUGS for the known
  issues (no file overwrite warning, so be carefull!)