[3.3.x] Saving options/kemaps produces garbled prf file

[PowerWyrm]

If you go to the '=' menu and save your options/keymaps a few times, you'll get an incorrect output in the prf file:

#=#=#=#=#=#=#=#=#=#=#=#=#=#=#=#=#=#=#=# end Dump options
#=#=#=#=#=#=#=#=#=#=#=#=#=#=#=#=#=#=#=# end Dump options
#=#=#=#=#=#=#=#=#=#=#=#=#=#=#=#=#=#=#=# end Dump keymaps
#=#=#=#=#=#=#=#=#=#=#=#=#=#=#=#=#=#=#=# end Dump options
#=#=#=#=#=#=#=#=#=#=#=#=#=#=#=#=#=#=#=# begin Dump keymaps
# *Warning!*  The lines below are an automatic dump.
# Don't edit them; changes will be deleted and replaced automatically.

#  keymaps definitions

A:[Escape]q1

C:0:[F1]

# *Warning!*  The lines above are an automatic dump.
# Don't edit them; changes will be deleted and replaced automatically.
#=#=#=#=#=#=#=#=#=#=#=#=#=#=#=#=#=#=#=# end Dump keymaps
#=#=#=#=#=#=#=#=#=#=#=#=#=#=#=#=#=#=#=# begin Dump options
# *Warning!*  The lines below are an automatic dump.
# Don't edit them; changes will be deleted and replaced automatically.

#  options definitions

...

# Window 'Term-7', Flag 'Display borg status'
W:7:15:0

A:[Escape]q1
C:0:[F1]

# *Warning!*  The lines above are an automatic dump.
# Don't edit them; changes will be deleted and replaced automatically.
#=#=#=#=#=#=#=#=#=#=#=#=#=#=#=#=#=#=#=# end Dump options

The code that removes the old part of the dump seems to forget to remove the footer...

[Magnate]

Opened as #1591, thanks. Maybe this will finally motivate us to fix the whole set of issues around loading and saving of preferences.