Added a git ignore file.
Added Composer configuration.
Added PHPUnit configuration files. Removed the tests from the autoload paths in composer config.
Added a Travis configuration file.
Added the Primitive abstract class.
Added the NotImplementedException class.
Fixed a typo.
Fixed typo.
Added the String primitive and concrete class along with the tests for it.
Fixed a grave error where the value() function called itself again and again instead of the attribute value.
Improved the String::is() function.
Added more tests for the String class.
Forgot to add the TestCase to the repo. This is the class all test derive from.
Added the Numeric abstract primitive along with a concrete implementation and some tests.
Moved the isEqual() function definition to the Primitive class.
Renamed variable names.
Slightly modified how the values to work with are computed.
Added and fixed docblocks.
Added the isEqual() function to the String class.
Fixed the docblocks and introduce parameter validation in the functions.