remove unused code in AgentSet classes

not just unused, but could be dangerous if used -- see comment removed
from ArrayAgentSet
fix broken links in User Manual
fix theoretical bug in new StructureParser

might affect error messages under some circumstances, not really sure
update comment in headless.Dump
update comment
remove debugging output
as far as we know, NetLogo works on Windows 8
slight wording change on downloads page
Keeping around some stuff in 'NetLogoLite' for the Web Image extension
Merge branch 'topic' into 5.0.x
Merge pull request #401 from NetLogo/remove-unused-agentset-methods

remove unused code in AgentSet classes
make `file-open` dictionary entry mention multiple open files
scalastyle now available for sbt 0.13
upgrade to ScalaTest 2.0.M6

I forget why I got the master branch on the ScalaTest 2.0 milestone/RC
upgrade train in the first place, but nonetheless, now that we're on
it, I feel responsible that we should stay on it until we have arrived
at a stable 2.0 release

(some good news is, I've been using 2.0 milestones and snapshots on
the headless branch witp no real problems)

changes needed to get compiling/running again:
- FunSuite is now a class not a trait, so I had to adjust the
  "extends" clause of some of our test stuff, and make a few of our
  classes into traits
- due to deprecation, renamed expectResult -> assertResult everywhere
- fixed a mistaken return type for a use of withFixture
bin/benches.scala: ensure tmp directory exists
bin/benches.scala: don't warn if tmp already exists
Merge pull request #428 from NetLogo/scalatest-2.0.M6-upgrade

upgrade master to ScalaTest 2.0.M6
Merge remote-tracking branch 'origin/master' into core

Conflicts:
	headless/src/main/org/nlogo/agent/World3D.java
	headless/src/test/org/nlogo/agent/World3DTests.scala
	headless/src/test/org/nlogo/api/ColorTests.scala
	headless/src/test/org/nlogo/api/VectTests.scala
	headless/src/test/org/nlogo/headless/TestImportExport.scala
	headless/src/test/org/nlogo/hubnet/mirroring/ClientWorldTests.scala
	headless/src/test/org/nlogo/hubnet/mirroring/DiffBufferTests.scala
	headless/src/test/org/nlogo/hubnet/mirroring/OverridableTests.scala
	headless/src/test/org/nlogo/lex/TokenMapperTests.scala
	headless/src/test/org/nlogo/lex/TokenizerTests.scala
	headless/src/test/org/nlogo/parse/AutoConverter1Tests.scala
	headless/src/test/org/nlogo/parse/AutoConverter2Tests.scala
	headless/src/test/org/nlogo/parse/ExpressionParserTests.scala
	headless/src/test/org/nlogo/parse/LiteralParserTests.scala
	headless/src/test/org/nlogo/plot/PlotLoaderTests.scala
	headless/src/test/org/nlogo/sdm/LoaderTests.scala
	headless/src/test/org/nlogo/sdm/ModelTests.scala
	src/test/org/nlogo/app/InfoConverterTests.scala
	src/test/org/nlogo/app/InfoFormatterTests.scala
	src/test/org/nlogo/log/LoggerTests.scala
Merge commit '189d12c3173bbf61a631461ff01b30cf2ccfc531' into headless

Conflicts:
	headless/src/main/org/nlogo/agent/World3D.java
Merge commit '815b3d94d4f19c02b191a8a781aa6bc73b844309' into headless

Conflicts:
	headless/src/main/org/nlogo/parse/StructureParser.scala