fix topology regression from Scala conversion

appears I was careless
fix regression in Color.getClosestColorNumberByHSB

dates back to when it was converted in Scala in 2011
oops fix wrong type in Optimizer

thanks 2.11 compiler for noticing!
rename a class to make more sense
cleanup: change `var` into `val`, because we can
remove unused imports
cleanup: change `var` into `val`, because we can
remove unused imports
remove unused code
remove unused code
minor cleanup (change var to val)
remove unused import
fix recent regression in Color

missing piece of 78b206d0beec55bbe3c0fed5b9e4e72200962c3f
add Travis CI config on headless branch
Merge remote-tracking branch 'origin/headless' into sbt-0.13