anchor.diff:  to support a new toolset will offset the time it takes to tell the build
   system about it by several orders of magnitude.
   
  +<<<
  +
   == Hello, world ==
   
   A Tundra project needs atleast two files, one is +tundra.lua+ which specifies
  
positive.code: }
  -------------------------------------------------------------------------------
  
  As you can see, it refers to another file, +units.lua+. The +Units+ file is a
  declarative input file describing the targets that are available:
  
  -------------------------------------------------------------------------------
  Program {
      Name = "HelloWorld",
      Sources = { "hello.c" },
  }
  Default "HelloWorld"
  -------------------------------------------------------------------------------
  
  If we now run Tundra on this input, it will build our +HelloWorld+ executable.
  The output path shows that tundra has defaulted the variant to `debug` and the
  
negative.code: }
  -------------------------------------------------------------------------------
  
  <<<
  
  == The Environment ==
  
  Tundra uses a hierarchical key-value environment to store information used to
  