added scalacheck to build

GitHub issue #23 - Migrate unit tests to ScalaCheck
added scalatest to build

GitHub issue #23 - Migrate unit tests to ScalaCheck
tweaking build to get scalatest working

GitHub issue #23 - Migrate unit tests to ScalaCheck
updated test package names

GitHub issue #23 - Migrate unit tests to ScalaCheck
got scalatest working alongside surefire

GitHub issue #23 - Migrate unit tests to ScalaCheck
adapted ExpressionProperties and Literal* test classes from reb4s

GitHub issue #23 - Migrate unit tests to ScalaCheck
made MultiChar constructor public

GitHub issue #23 - Migrate unit tests to ScalaCheck
bumped minor version

GitHub issue #23 - Migrate unit tests to ScalaCheck
adapted UtilGenerators and CharClass testing support from reb4s

GitHub issue #23 - Migrate unit tests to ScalaCheck

GitHub issue #23 - Migrate unit tests to ScalaCheck
adapted Adopted test from reb4s

GitHub issue #23 - Migrate unit tests to ScalaCheck
made Raw.EscapedLiteral constructor public for testing purposes (should not be used in applications, but doesn't hurt anything if it is)

GitHub issue #23 - Migrate unit tests to ScalaCheck
cleaned up imports

GitHub issue #23 - Migrate unit tests to ScalaCheck
adapted Raw tests from reb4s

GitHub issue #23 - Migrate unit tests to ScalaCheck
added Mode enum to Quantified

GitHub issue #23 - Migrate unit tests to ScalaCheck
created classes for group types

GitHub issue #23 - Migrate unit tests to ScalaCheck
created classes for the different types of quantified expressions

GitHub issue #23 - Migrate unit tests to ScalaCheck

GitHub issue #23 - Migrate unit tests to ScalaCheck

GitHub issue #23 - Migrate unit tests to ScalaCheck
adapted Expression tests from reb4s

GitHub issue #23 - Migrate unit tests to ScalaCheck

GitHub issue #23 - Migrate unit tests to ScalaCheck
corrected AdoptedProps

GitHub issue #23 - Migrate unit tests to ScalaCheck
added missing calls to check

GitHub issue #23 - Migrate unit tests to ScalaCheck
adapted dotted decimal test from reb4s

GitHub issue #23 - Migrate unit tests to ScalaCheck