Exception: fix typo in error message
cme: load Tk only when using edit command (avoids issues with AnyEvent)

Pb: When loading Tk, AnyEvent load its glue module between Tk and AnyEvent.
this one complains on destruction if no main Tk window was created.
Value: improved traces
cme: make sure that async store is used before actual check

by forcing load of all node and then running dump_tree
Node has_element: small optimisation for common case
v2.035