- Added control_names for the "Show Advanced Menu" and "QAMode" checkboxes

 after loss during cleanup of preferences.

Reason: The old shortcut (Ctrl+Alt+D) was eaten by some window managers.

Changes:
- Changed the shortcut to Ctrl+Alt+Shift+D.
- Moved the appropriate menu item from "Advanced > Shortcuts" to "World > Show"
  (so that it's not in the menu it triggers) and made it visible.
  The old shortcut is still available but marked as legacy.

Submitting on behalf of Boroondas Gupte.

The editor can be specified:
* via "ExternalEditor" setting in settings.xml
* via LL_SCRIPT_EDITOR variable

Removed obsolete XUIEditor setting in favor of the new one.

This changeset also covers STORM-572 (note that design in this fix differs a little from the one proposed in there because there was not enough space to make it that way).

- Removed controls:
    1. "Move avatar lips when speaking" checkbox
    2. "Toggle speak on/off when I press:" checkbox
    3. "Push-to-Speak trigger" lineeditor
    4. "set_voice_hotkey_button" button
    5. "set_voice_middlemouse_button" button

- Set proper names for checkboxes

According to the specification these controls are in the Sound&Media panel now.

 and also changed the name used for P2P IM log file names. The latter change is going to
 temporarely break personal content for those that are saving conversation logs as P2P IM
 logs will now be useinf the user name and not the legacy name.

- Temporary restored controls:
    1. "Move avatar lips when speaking" checkbox
    2. "Toggle speak on/off when I press:" checkbox
    3. "Push-to-Speak trigger" lineeditor
    4. "set_voice_hotkey_button" button
    5. "set_voice_middlemouse_button" button

They should be moved to the Sound&Media panel of floater Preferences. But the specification for the Sound&Media panel is not ready yet.
As specification will be ready, these controls will be moved to the Sound&Media panel.

- According to the specification deleted all controls except:
    1. "UI Size" slider
    2. "Show script errors in" radio group

- According to the specification:
    1. "Allow Multiple Viewer" checkbox
    2. "Show Grid Selection at login" checkbox
    3. "Show Advanced Manu" checkbox
    4. "Show Developer Menu" checkbox

STORM-583 ADDITIONAL_FIX Fixed top_pad of topmost control in "Colors" so that it is consistent with other preferences tab.

- Deleted Mouselook settings

- Increased vertical padding between "Cache size" and "Cache location" controls

STORM-582 FIXED Moved movement and camera control preferences from Advanced to the new Move & View tab.

In addition to moving existing controls, created stub checkbox and radiobuttons for double-click behavior. Logic will be hooked up to them in STORM-576.

- Increased vertical paddings between checkbox groups

- Changed label of IM checkbox group from "Logs:" to "Chat Logs:"

- Changed label of checkbox from "Add timestamp" to "Add timestamp to each line in chat log"

- Added checkbox "Add datestamp to log file name". For now this checkbox is not working, it's just a stub for a future functionality.

- Added descriptive text for the "Block List" button

- Decreased vertical padding between controls to insert radio group

- Added "Pressing letter keys:" radio group.

For now these radio buttons are not working, they are just a stub for a future functionality.