Rearranged the package directory hierarchy so that all the Python files are contained within a new 'pyaixi' subdirectory. This is to ultimately make a 'pyaixi' package name consistently available to scripts when run directly from a release archive, as well as after installation.
In aixi.py: fixed module imports so that this script works correctly from the final installed path as well as when run from within a release archive. Agents and environments without explicit package prefixes are now given a default prefix of 'pyaixi.agents.' or 'pyaixi.environments.', so that dynamic loading of these by bare module name still works with the module import changes.
In pyaixi/: modified module imports and package search path manipulation so that this works correctly with the new directory hierarchy when the aixi.py script is run from within a release archive, as well as when installed.
In setup.py: removed the package_dir entry, as this is no longer needed with the new directory hierarchy.
In doc/changelog.txt: added a note about the 1.0.3 release, which changes the directory hierarchy (adding a containing 'pyaixi' directory) to fix an import issue with the aixi.py script when run from the final installed location.
In setup.py: bumped the version number for the 1.0.3 release.