instead of relying on Scintilla undo actions, use SciTECO undo tokens exclusively

Previously we were using both Scintilla undo actions and our own undo tokens
and both had to be coordinated via `undo__teco_interface_ssm(SCI_UNDO, 0, 0)`.
This was error prone since we have to predict when an undo action is actually
generated. Furthermore, you had to update SCI_SETUNDOCOLLECTION on all buffers
and the Q-Reg view whenever switching to and from interactive mode.
Also, this probably wasted memory for the doubled undo bookkeeping.
Now, we always set SCI_SETUNDOCOLLECTION(FALSE), even in interactive mode.
teco_undo_view_insert() was introduced to undo text deletions.
While this saves almost no lines of code, it's just a clearer and simpler
architecture.

0 files changed, 0 insertions, 0 deletions