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.
svn merge -r 129913:131718 svn+ssh://svn.lindenlab.com/svn/linden/branches/pluginapi/pluginapi_05
Some branch shenannigans in the pluginapi_05 branch caused this to become a two-part merge.