allow changing the default clipboard by setting the `~` integer

* It continues to default to 67 (C), which is the system clipboard.
  But you can now overwrite it e.g. by adding `^^PU~` to the profile.
* This fixes a minor memory leak:
  If you set one of the clipboard registers in the profile (initializing
  them as plain registers), the clipboard register had been leaked.
  The clipboard registers now replace any existing register,
  while at the same time preserving the numeric part.
* All remaining Q-Reg table insertions use a new function
  teco_qreg_table_insert_unique() which adds an assertion, so that
  we notice any future possible memory leaks.

1 files changed, 0 insertions, 0 deletions

diff --git a/fallback.teco_ini b/fallback.teco_ini
index 72c13f7..cee87dc 100644
--- a/fallback.teco_ini
+++ b/fallback.teco_ini