Automation: AudacityCommand

This is a squash of 50 commits.

This merges the capabilities of BatchCommands and Effects using a new
AudacityCommand class.  AudacityCommand provides one function to specify the
parameters, and then we leverage that one function in automation, whether by chains,
mod-script-pipe or (future) Nyquist.

- Now have AudacityCommand which is using the same mechanism as Effect
- Has configurable parameters
- Has data-entry GUI (built using shuttle GUI)
- Registers with PluginManager.
- Menu commands now provided in chains, and to python batch.
   - Tested with Zoom Toggle.

- ShuttleParams now can set, get, set defaults, validate and specify
the parameters.
- Bugfix: Don't overwrite values with defaults first time out.
- Add DefineParams function for all built-in effects.
- Extend CommandContext to carry output channels for results.

We abuse EffectsManager.  It handles both Effects and
AudacityCommands now.  In time an Effect should become a special case of
AudacityCommand and we'll split and rename the EffectManager class.

- Don't use 'default' as a parameter name.
- Massive renaming for CommandDefinitionInterface
- EffectIdentInterface becomes EffectDefinitionInterface
- EffectAutomationParameters becomes CommandAutomationParameters
- PluginType is now a bit field.

This way we can search for related types at the same time.

- Most old batch commands made into AudacityCommands.
The ones that weren't are for a reason.  They are used by mod-script-pipe
to carry commands and responses across from a non-GUI thread to the GUI
thread.

- Major tidy up of ScreenshotCommand
- Reworking of SelectCommand
- GetPreferenceCommand and SetPreferenceCommand
- GetTrackInfo and SetTrackInfo
- GetInfoCommand
- Help, Open, Save, Import and Export commands.
- Removed obsolete commands ExecMenu, GetProjectInfo and SetProjectInfo
  which are now better handled by other commands.

- JSONify "GetInfo: Commands" output, i.e. commas in the right places.

- General work on better Doxygen.
    - Lyrics -> LyricsPanel
    - Meter -> MeterPanel
- Updated Linux makefile.
- Scripting commands added into Extra menu.
- Distinct names for previously duplicated find-clipping parameters.
- Fixed longstanding error with erroneous status field number which
  previously caused an ASSERT in debug.
- Sensible formatting of numbers in Chains, 0.1 not 0.1000000000137

src/commands/HelpCommand.h

@@ -22,20 +22,23 @@
 #include "CommandType.h"
 #include "Command.h"
 
-class HelpCommandType final : public CommandType
+#define HELP_PLUGIN_SYMBOL XO("Help")
+
+class HelpCommand : public AudacityCommand
 {
 public:
-   wxString BuildName() override;
-   void BuildSignature(CommandSignature &signature) override;
-   CommandHolder Create(std::unique_ptr<CommandOutputTarget> &&target) override;
+   // CommandDefinitionInterface overrides
+   wxString GetSymbol() override {return HELP_PLUGIN_SYMBOL;};
+   wxString GetDescription() override {return _("Gives help on a command.");};
+   bool DefineParams( ShuttleParams & S ) override;
+   void PopulateOrExchange(ShuttleGui & S) override;
+   bool Apply(const CommandContext & context) override;
+
+   // AudacityCommand overrides
+   wxString ManualPage() override {return wxT("Help");};
+public:
+   wxString mCommandName;
 };
 
-class HelpCommand final : public CommandImplementation
-{
-public:
-   HelpCommand(HelpCommandType &type, std::unique_ptr<CommandOutputTarget> &&target)
-      : CommandImplementation(type, std::move(target)) { }
-   bool Apply(CommandExecutionContext context) override;
-};
 
 #endif /* End of include guard: __HELPCOMMAND__ */