hop_tasks: dartdoc: tell users about --allow-dirty flag if task fails
hop_tasks: unittest: added createDartDocTask

smarter defaults for most arguments, using named arguments

deprecate getCompileDocsFunc and compileDocs
hop_tasks: dartdoc: allow overriding targetBranch with command arg
hop: dartdoc: createDartDocTask now supports optional 'postBuild' arg
tool: generalizing some helpers
hop: logging start time, end time, duration at low level
pub: updated min version of html5lib, adding pathos
tool: post-build fun for documentation
resources for docs
tool: docs post-build updates images, adds logo, links