Fix issue #75 : Add File/Set Log File menu item
Checked if a log file is currently Open
The log file is used for all local graphs while it is open
Selecting the item a second time closes the log file
Opening an existing log file clears the file first
The log file is Unicode 
The log file can be read will it is open (e.g. by a 'tail' type tool)
Menu item is always disabled and unchecked for remote graphs as remote graphs can't use the local file handle.

git-svn-id: http://graph-studio-next.googlecode.com/svn/trunk@189 c2f33eb2-41b2-391d-4cb4-d9d0608729ba
Updated version number to 0.6 - lots of features added since r117!


git-svn-id: http://graph-studio-next.googlecode.com/svn/trunk@190 c2f33eb2-41b2-391d-4cb4-d9d0608729ba