upgrade to ScalaCheck 1.11.0

for now this requires a special snapshot build of ScalaTest.
we shouldn't merge this until that has been sorted out.
see https://github.com/scalatest/scalatest/issues/181
add precision regarding view updates to tick-advance doc
add some model thumbnails to the 'what is NetLogo' page in the doc
get update gogo extension (to get updated .gitignore)
get rid of a curricular model that sneaked into checksums.txt
get rid of some false positives for spell checking models
get rid of a few more false positives in dist/modelwords.txt
update models library
keep pointing to element in dashChoices when cloning link line (for #517)
change default link shape for #516
parse invisible link lines as lines with empty strokes (see #516)
swap left and right combo boxes in link shape editor (#518)
Merge pull request #519 from NetLogo/link-shape-manager-issues

Link shape manager issues
Bumping 'bin/issues.scala' to look at 5.0.5 issues
Adding Frank to the list of developers
user manual: fix grammar mistake
update models
Updates for 5.0.5 release

(cherry picked from commit 8e37210b22f178368d13a704d62b85c1a4233324)
Version update for 5.0.5 final

(cherry picked from commit 0f3aa60518432b6f3a1fd581132afdf33554e510)
Reinstating the mighteous order of INTERIM DEVEL BUILD