minor cleanup

doc/TODO.txt

@@ -37,10 +37,6 @@ Using STL-imported models is tricky and triggers multiple issues:
      import_stl("adns2610_dev_circuit_inv.stl");
    }
 
-CRASH BUGS
-----------
-o Broken polyhedron() entities are not correctly detected and cause CGAL segfaults
-
 USER INTERFACE
 --------------
 o Preferences
@@ -72,13 +68,8 @@ o 3D View
   - View All
   - Allow specifying viewpoint in the scad file
   - overlay indicator displaying current view mode
-  - OpenCSG rendering: Coincident surfaces causes z-buffer fighting. Is this somehow
-    avoidable tuning the depth tests in OpenCSG? 
-  - Make the 10.000 element OpenCSG limit configurable (Preferences) ?
   - Use OpenGL picking to facilitate ray-tracing like features like measuring
     thicknesses, distances, slot thicknesses etc.
-  - When specifying a transparency with the color() statement,
-    the object is not sorted and will be rendered wrongly
   - Add option to change lights, e.g. add an optional camera light
 o Editor wishlist
   - More infrastructure for external editor (allow communication from the outside)
@@ -122,6 +113,16 @@ o Misc
 o Cmd-line
   - Add verbose option (PRINT command from mainwin.cc and progress output)
 
+OpenCSG-related
+---------------
+o OpenCSG rendering: Coincident surfaces causes z-buffer fighting. Is this somehow
+  avoidable tuning the depth tests in OpenCSG? 
+o Make the 10.000 element OpenCSG limit configurable (Preferences) ?
+o When specifying a transparency with the color() statement,
+  the object is not sorted and will be rendered wrongly
+o Bug: Using the background operator (%) on the only object in a scene triggers a
+  CSG error: No top level object found
+
 ENGINE
 ------
 o Primitives
@@ -149,7 +150,6 @@ o Language Frontend
   - Rethink for vs. intersection_for vs. group. Should for loops
     generate child lists instead, and make these passable to other
     modules or accessible by child()?
-  - constants: PI, OpenSCAD version
 o DXF Import/Export
   - Use dxflib from RibbonSoft for import/export? -> investigate
   - Import
@@ -167,8 +167,6 @@ o Misc
   - Add 'lines' object type for non-solid 2d drawings
   - Is there a reason why modules like echo, empty if, empty for loop returns an
     empty AbstractNode instead of being ignored?
-  - Bug: Using the background operator (%) on the only object in a scene triggers a
-    CSG error: No top level object found
   - Dependency tracking of libraries (USE'd modules) isn't implemented. See Mail from nophead 20110823.
 o Grammar
   - dim->name -> dim->label
@@ -219,8 +217,8 @@ INFRASTRUCTURE
 o Use a logging framework to get debugging/info output more under control?
   (check log4j, google project)
 
-MISC
-----
+DOCUMENTATION
+-------------
 o Write checklists for typical extension work (add new module, add new function)
   -> make sure new test files are added