Maintenance version.

Improvements

core updated Scala 2.12.0-RC1
core update scalaz to 7.2.6
cats update cats to 0.7.2
scalacheck updated scalacheck to 0.13.2
gwt updated shapeless to 2.3.2
core remove all empty text and formatting fragments when filtering by tag and replace with a newline before each example
core limit the scope of ArgProperty to limit the possible impact of the implicit conversions to ArgProperty
scalacheck keep the stacktrace of a Failure created in a ScalaCheck property
matcher-extra renamed a source directory for matcher-extras
markdown removed the shapeless dependency on markdown and specs2-form
project added a link to paypal.me

Fixes

core re-throw Timeout failures in mutable specifications when using FutureMatchers
core evaluate results only once in the Result Monoids #496
core use flattenLeft to flatten a tree instead of flatten to avoid stackoverflow exception with the JUnit notification on large specifications
core fail a sbt run if there is an error in one of the steps (this includes the afterAll steps)
core fixed a NoSuchElementException when folding with a Sink #501
scalacheck report an AssertionError as a Failure in ScalaCheck and display arguments on exceptions
scalacheck fixed the use of datatables in ScalaCheck properties
gwt fixed an error in the example of GWT style
project fixed the google groups link
guide fixed a package name in the user guide
guide add missing imports to "Create Your Own" matchers section #493 (by Kris Nuttycombe)
markdown fixed the markdown spec which was broken after using pegdown 1.6.0. The post-processing of multilines in code blocks can not be easily done anymore so it was removed