gnucash master: Multiple changes pushed

[John Ralls]

Updated	 via  https://github.com/Gnucash/gnucash/commit/1341511e (commit)
	 via  https://github.com/Gnucash/gnucash/commit/cdb674eb (commit)
	from  https://github.com/Gnucash/gnucash/commit/c474d81e (commit)



commit 1341511edb7e8166867b6d7069841bbb1b2dbddd
Author: John Ralls <jralls at ceridwen.us>
Date:   Mon Mar 6 15:36:23 2023 -0800

    [c++options] Save an empty SCM string for nil or empty option values.
    
    Avoids crash at reload due to unknown variable.

commit cdb674ebf1d097cb2c15a71f07426a0c1ae12f36
Author: John Ralls <jralls at ceridwen.us>
Date:   Mon Mar 6 11:43:50 2023 -0800

    [c++options]Really fix the gnc_option_db_lookup_string_value leak
    
    By deleting the function and using GncOptionDbImpl::lookup_string_option
    directly. It returns a string that we don't have to worry about
    memory-managing.
    
    Also create a new GncOptionDbImpl::set_string_option to replace
    gnc_option_db_set_string_value.



Summary of changes:
 bindings/guile/gnc-optiondb.i            | 30 ++++++++---------------
 gnucash/gnome/gnc-plugin-page-report.cpp | 42 +++++++++++++++-----------------
 libgnucash/engine/gnc-optiondb-impl.hpp  |  4 +++
 libgnucash/engine/gnc-optiondb.cpp       | 15 ------------
 libgnucash/engine/gnc-optiondb.h         | 28 +--------------------
 5 files changed, 35 insertions(+), 84 deletions(-)