gschem: Add feature to reset refdes when copy and pasting
gattrib: Fix non-ASCII 'o' character
gschem: Store displayed node names in tree model
gschem: Add direct attribute mapping for displayed symbol names
gschem: Remember which library nodes represent symbols
gschem: Move symbol library population into separate function
gschem: Add subdirectory source nodes as parent directory's children
gschem: Display library folder structure as tree

Tested-by: Kai-Martin Knaak <knaak@iqo.uni-hannover.de>
Add include directives for locale.h
gschem: Run %copy-objects-hook for copy and copy multiple modes
gschem: Make bottom widget show middle button function consistently
gschem: Successive pastes run the %copy-objects-hook

By adding the following lines to the gschemrc file, gschem will reset refdes on component
copies, and avoid duplicate refdes.

(load-from-path "auto-refdes.scm")
(add-hook! copy-objects-hook auto-refdes-reset!)

Additional refactoring moves variables from global scope to file scope.