Proposal Effect Menu Categorization

The Problem
The Effect Menu is too long to display on the screen without scrolling and grows even longer if users add their own effects. Most users use only a small subset of these effects and finding the ones they need in the long list is difficult (and requires at least two or more clicks).

A typical user's use of effects means that they will use a small subset - but each item will be used many times in the editing process.

Users have complained about the length of the menu.

Proposed Feature
Categorization of effects in the menu, customizable by the user.

Developer/QA Backing

 * Peter
 * Steve
 * I feel that a key aspect in making this acceptable to all, is that the user must be able to easily organize their effects into groups in the way they want, rather than the "filing scheme" being imposed by the design. The "factory default" groups could be simply "built in effects" and "plug-ins" (as now).
 * Gale
 * Must support all effects formats. The previous implementation totally ignored VST effects.
 * Must be uncategorised by default but with an easily visible way to turn it on without going into Preferences. Perhaps it is simply "always on" but not yet customised (press a button to access a keyboard-friendly categorisation dialog). If we allow mouse drag of effect menu items and right-click over the effect menu > New Category, there should be some kind of lock that has to be turned on before you can do that.

Use Cases

 * Many complaints on the Forum regarding the length of this menu.
 * Users who used the categorization that was in 1.3.6-beta frequently request its return
 * Some posters on the Forum, with programming skills, are instructed how to build Audacity with the 1.3.6 categorization turned on.

Details

 * Allow the Effects drop-down menu to have the capability for sub-folders or categorization so that the user can organize their plug-ins however they wish.
 * A "Favorites" folder to be provided that is nothing to do with the automatically generated structure (about one-third of voters for this feature want this).
 * A new Preferences setting to be provide to facilitate turning categorization on/off (default to be "off").
 * Restrict the auto-generated subfolder to only 2 levels deep (Effects > Category), not 3 levels as tried before in 1.3.6 (Effects > Category > Sub Category) but do not restrict to Two levels if the user optionally requires sub-levels.
 * With just one level of categories, the menu will open by hovering the mouse, making locating a specific effect much quicker and easier.
 * Provision to be made for the user to customize their categories, change and sort their entries.
 * Gale 13Nov13: I think it's accepted there will be (at least) a dialogue to do this, so that it's keyboard friendly. There are growing requests for some kind of "plug-in manager" where user can enable/disable particular effects, choose in which folders Audacity detects different types of plug-ins and so on. Should the categorisation dialog be in such a manager, or designed so that it could be moved into such if it is subsequently developed?
 * Set the menu to automatically detect and display subfolders of the Plug-Ins folder as categories.
 * Gale 13Nov13: This seems attractive but there is the issue of how plug-ins in system folder structures are accommodated. Do we need this if the feature is fully customisable anyway (which I think it needs to be)?

GUI Examples
TBP