[Lazarus] IDE Desktops redesign

[Ondrej Pokorny]

According to some recent discussions and bug reports, I plan to rework 
the Desktops feature in the IDE. Before I again get a "Please stop the 
IDE regressions!" messages, I decided to announce and discuss the topic 
in the mailing list in advance.

The redesign will include the following points:

1.) Removal of IDE Options -> Environment -> Windows -> Window Positons.
Why: The desktop features duplicate "Restore window geometry" and 
"Custom window geometry" settings. The other two settings ("Let 
windowmanager decide" and "Fixed default geometry") seem useless for me. 
The options also conflict with Desktop window layout.
Column widths and other window layout settings will be saved through new 
generic interface.

2.) Moving options that are saved in the desktop into new IDE Options 
category "Desktop" (within the same IDE Options dialog).
"Environment -> Window" :: "Desktop -> Window"
"Environment -> IDE coolbar" :: "Desktop -> IDE coolbar"
"Environment -> Editor toolbar" :: "Desktop -> Editor toolbar"
"Environment -> AnchorDocking" :: "Desktop -> AnchorDocking"
Why: just to make sure people understand that these settings are saved 
in the Desktop and change when Desktop is changed and that they are not 
IDE-wide.

3.) User-configurable options (from IDE Options) will be always auto 
saved just like all other options are. The "auto save" setting from 
Desktop Manager will affect only window layout that is not manually 
configurable.

Ondrej