0.7.2: Fix documentation and composer dependencies

Documentation now properly defines what a variable name is.
Dependencies are now properly defined for older PHP versions.

0.7.1: Accessing an array with a negative index now behaves as expected

Bug fix array negative index

0.7.0: Set creates non-existent intermediate objects

Set now creates non-existent intermediate objects

0.6.0: Added custom exceptions

Added custom Exception classes. Other minor fixes.

0.5.1: Removed versioning from the composer.json file to allow tag based

management

0.5

Fixed name package name in composer.json