Revert "Fix bad qof_instance crash in dialog-payments"

This reverts commit edd85faad75055231cc58779d2c677fc61cc9492.
Revert "Fix typo in test-engine-kvp-properties."

This reverts commit ac9a6ae606e67f8ca7a7fffd75a7f6c8dcc75060.
Revert "Merge branch 'private-kvp'"

This reverts commit f49983b8012197933c793fe94994ac5afa1d8d75, reversing
changes made to acad5a02bbc04cb17b33c89ed36d839416db8f10.
Merge branch 'private-kvp' into master again

This was done by branching right before the original merge
and redoing a clean merge of the private-kvp branch again.

This result was then cherry-picked onto master with
git cherry-pick <merge-commit> -m 1

It was done like this because git merge would consider
the private-kvp branch already merged even after a revert
(see git-revert man page) and won't allow to merge a
second time on the same branch.

Resolved conflicts:
	README.dependencies
	src/app-utils/gnc-sx-instance-model.c
	src/engine/cap-gains.c
	src/engine/test/Makefile.am
	src/gnome/assistant-hierarchy.c
	src/import-export/import-match-map.c
	src/import-export/import-utilities.c
	src/import-export/ofx/gnc-ofx-kvp.c
	src/libqof/qof/qofbook.cpp
	src/libqof/qof/qofinstance-p.h
	src/libqof/qof/qofinstance.cpp
	src/libqof/qof/test/test-kvp_frame.c
	src/report/report-gnome/gnc-plugin-page-report.c
Fixes necessary to marry private-kvp branch with c++ work
Reapply "Fix typo in test-engine-kvp-properties."

This reverts commit c475b9f8c7545e1f4dc3b1e0a3b9b6b217a30719.
Reapply "Fix bad qof_instance crash in dialog-payments"

This reverts commit b81289acc66340c74a4b7ed32d0dfffef4a87c16.