FEATURE: added test for issue #451
REFACTORING: corrected the name for test "step_plot_per_series"
BUGFIX #451: fixed "connect-separated-points" bug
TEST: adapted test for bugfix
REFACTORING: use the method "getLeftBoundary" instead of a private
variable
BUGFIX: bugfix for issue #451 is now also working for bars
FEATURE: extended test for the bugfix for issue #451
EXAMPLE: added new example for fixed bug
REFACTORING: adapted EOL
REFACTORING: fixed jslint violation
Merge commit '9f890c23ad80924d0a30f3a14f8680b7c2d6318e' into fix-for-issue-451

Conflicts:
	dygraph-layout.js
REFACTORING: Fixed code style nits and extracted the null values check to a method.
REFACTORING: fixed code style and lint warnings. Readded jsdoc lost in merge.
Merge pull request #243 from sauter-hq/fix-for-issue-451

Fix for issue 451