simplify TokenMapper now that it's 2D-only
remove now-unused code

this stuff was only used by AutoConverter, which we got rid of on the
headless branch
remove now-unused code

this stuff was only used by agent monitors in the GUI
shuffle code out of api package into Optimizer

cleaner since the methods were only ever used in Optimizer
add comment
headless branch: drop Java 6 support, move to 7
headless branch: bring extensions up to date
update TestCompileAll for removal of sound extension on headless branch
update checksums for switch to Java 7

Oracle fixed an old issue where some Doubles printed with a trailing
zero. that made some world checksums change. I admit I didn't actually
check every single model that was failing to see if that was the
cause, but I did check several
graffle update
fix regression on Java 7 where MethodSelector sometimes chose wrong

it was because apparently Oracle did something that made
getMethods sometimes return methods in a different order.
our code should have been robust about that, but it wasn't.
now it is.
cleanup: use 'private' less in generate package

we're already using Classycle to ensure that nothing has any
compile-time dependencies on generate, so there isn't much point in
declaring the classes and objects there private. (and anyway having
stuff private interferes with testing things in the Scala REPL)
clean up how model checksumming is handled

in preparation for adding __checksum primitive.  but also just
generally removing tangles just because
add __checksum primitive

this is useful for interactive testing, such as in the NetLogo REPL
make bin/shell.sh aware of JAVA_HOME

this is useful e.g. on monk2 where Java 7 is available but isn't
the default JVM.
update models repo

to get Expected Value Advanced preview commands fix
oops, fix silly mistake in recent Checksummer cleanup
small efficiency improvement in Checksummer
cleanup: make api.ModelCreator not be a trait

introducing an inheritance relationship this seems to me like not a
good way to avoid `import`, and there didn't seem to be any other
purpose to it
fix a place where ParserInterface depended on CompilerInterface

(context: we're trying to remove all dependencies of compiler front
end code on compiler back end and/or engine code)