Fix a bunch of GUILE_WARN_DEPRECATED warnings.

[Derek Atkins]

Log Message:
-----------
Fix a bunch of GUILE_WARN_DEPRECATED warnings.

	* src/gnc-module/gnc-module.scm: create (and export) a re-export macro
	  is guile doesn't already provide one.  Then re-export the symbols
	  instead of exporting them.  Fixes some deprecated guile warnings.
	* src/guile-mappings.h: convert scm_gc_{un,}protect_object() back
	  to its pre-1.6 type for earlier guiles, but upconvert to the new
	  type to fix a deprecated warning.  Note that g-wrap is still
	  outputting deprecated code.
	* lots of other files:
	  convert scm_{un,}protect_object -> scm_gc_{un,}protect_object because
	  the former is now deprecated in guile.  Fixes a bunch of
	  GUILE_WARN_DEPRECATED warnings (but probably not all of them).

Modified Files:
--------------
    gnucash:
        ChangeLog
    gnucash/src:
        guile-mappings.h
    gnucash/src/app-utils:
        gnc-component-manager.c
        guile-util.c
        option-util.c
    gnucash/src/backend/file:
        sixtp-utils.c
    gnucash/src/business/business-core:
        gncBusGuile.c
    gnucash/src/business/business-gnome:
        dialog-invoice.c
    gnucash/src/engine:
        engine-helpers.c
        gnc-session-scm.c
    gnucash/src/gnc-module:
        gnc-module.scm
    gnucash/src/gnome:
        dialog-progress.c
        window-acct-tree.c
    gnucash/src/gnome-utils:
        dialog-options.c
        gnc-menu-extensions.c
    gnucash/src/import-export/qif-import:
        dialog-account-picker.c
        druid-qif-import.c
    gnucash/src/register/ledger-core:
        split-register.c
    gnucash/src/report/report-gnome:
        dialog-column-view.c
        dialog-style-sheet.c
        window-report.c