That way plugins don't need to implement the SettingsPlugin mixin in order to access their data folder, which is now an injected property in OctoPrintPlugin. Plugin authors should still always use the getter since that will also make sure the folder actually does exist (lazy creation).
PluginSettings.get_plugin_data_folder has been marked as deprecated.
Added phase specific hooks for queuing, queued, sending and sent phases of a command ("octoprint.comm.protocol.gcode.<phase>"). Removed old queuing phase hook and declared as obsolete hook in plugin manager to prevent plugins that depend on it from being enabled.
Adding those new hooks also necessitated refactoring the whole command processing, made it more modular and added phase specific handler functions that allow handling all blocking commands centrally for example.
This will hopefully prevent conflicting routes between multiple plugins from being registered and also ensures a more consistent behaviour compared to BlueprintPlugin mixins.
Thanks to @Salandora for bringing this up.
The new hook allows extending the list of rules for maximum body sizes differing from the default of 100KB and can be used by plugins to allow uploads to them that exceed that file size.
Also extended the plugin manager to detect plugins that implement restart needing hooks (such as the above one) and handling those plugins the same as plugins containing implementations that inherit from octoprint.plugin.core.RestartNeedingPlugin
* moved virtual printer into plugin
* made default serial factory use supplied parameters instead of directly utilizing self._port and similar
* documented new hook
Multiple mixins are allowed of course. Allowing multiple implementations lead to too many problems due to plugin names for referring to the APIs of SimpleApiPlugins or the assets of AssetPlugins.
Hence __plugin_implementations__ has been deprecated in favor of __plugin_implementation__. The plugin subsystem will automatically copy the first implementation from __plugin_implementations__ to __plugin_implementation__ and log a deprecation warning.
Adjusted documentation accordingly. Also added docs for helpers.
