Adds variables pane to several of the Browsers, similar to old Smalltalk/V browsers.
NOTE: No longer adds an instance variable to the Browser class.
The variables pane is controlled by Preferences in the 'browsing'
category. Two options exist:
#showVarsInBrowser - toggles if variables pane is included in the browsers or not
#showInheritedVars - if the vars are enabled by the above option, this one controls
if inherited variables are shown or not. This option can be
disabled by a menu in the variables pane itself.
The variables pane includes menu items for searching for accesses and references to
a selected variable from the list too.
This code was tested for the full system browser and the class hierarchy browser. It
was verified to behave correctly.
Aside from the inclusion of this new optional browser pane, this change set makes no changes to other existing Browser code. It does have conflicts with the Refactoring Browser.