v0.4.0

Features

• Initial WebREPL support. See documentation and examples/09_webrepl. Performance is a bit lackluster, but should be acceptable for projects that don't need rapid response.
• Optimized some command/responses for less communication round-trips (slightly improves WebREPL performance).
• Allow main.py and boot.py in the sync folder. They don't actually impact Belay's ability to operate. Removed SpecialFilenameError that would have been previously raised if either of these were present.
• Added optional keyword argument keep to specify files on-device that should not be deleted if a corresponding file doesn't exist in the sync folder. Defaults to ["boot.py", "webrepl_cfg.py"], since these files may contain device-specific information.

Bug Fixes

• Fix sync hash-checking logic. Previously all files were always synced.
• Fix and improved erroneous message in ValueError raised by Device.sync

Internal

• Moved on-device code snippets into their own folder for easier maintenance.