Merge pull request #4 from 1500100900/master

Don't copy the script name, just have a pointer to point into it.
Compile every source file to an object file, then link it all together. This will make it compile only the files that have changed.
A side-effect that I'm hoping for is making it possible to compile flathead with compilers that have failed to do so due to linking errors.
Minor fix for value of a variable statement in repl.

- Because variable hoisting converted variable declarations with
  initialisers to assignments, the value of the assignment was sometimes
  bubbling up as the value of the variable statement (which is only
  visible with the repl).
Removes the extra newline before printing an object.
Merge branch 'master' of github.com:ndreynolds/flathead
Merge pull request #6 from 1500100900/makefile

Improve the makefile.