Mappersession

This version updates some libmapper-python enum constants to libmapper 2.4.6. It also improves the documentation for `load()` and `load_json()` to elaborate on wildcard-matching / mapping transportability.

Requires libmapper 2.4.6.

This version streamlines the required properties in the mapping file schema, resulting in more flexibility in importing older partially-compliant file types.

Requires libmapper 2.4.5.

This version adds the ability to set and retrieve multiple session tags per map.

In addition to bugfixes, this version adds a number of useful new features:

- a pre-initialized libmapper Graph object can now be passed as an option argument. In this case calls to create or destroy maps do not need to wait for the local Graph to synchronize with the network before proceeding.
- maps loaded from a session file are now tagged with the filename as metadata. This tag is used to support a new `unload` command/function which destroys maps tagged with the filename argument.
- each loaded file is now assigned its own libmapper control Signal, enabling files to be loaded/unloaded independently in any order and in parallel.
- Waiting for signals to appear before creating a map ("asynchronous load") has been separated from persistently recreating maps when signals (re)appear.

Bugfixes include:

- Devices that have been tagged as `hidden` are now excluded from saving and loading maps.
- Wildcard matching of device names has been restored. A new `device_map` argument has been added if specific device assignment is desired
- Loading a mapping session file no longer clears existing maps by default

Provides basic libmapper session saving and loading (with staging) functionalities.

If you're a user, you can install the module with `pip install mappersession`. Please refer to the README.md for usage instructions, and happy mapping! :)

Additional features:
- Loading/cycling through multiple sessions at once
- Direct implementation in (webmapper)[https://github.com/libmapper/webmapper/pull/33]