New function to open custom reports dialog with one report name in edit mode

git-svn-id: svn+ssh://svn.gnucash.org/repo/gnucash/trunk@23096 57a11ea4-9604-0410-9ed3-97b8803252fd
Implement Save and Save As for custom report templates

This fixes bug 649284 - Allow saving of Custom Reports without changing name, overwriting existing report

git-svn-id: svn+ssh://svn.gnucash.org/repo/gnucash/trunk@23097 57a11ea4-9604-0410-9ed3-97b8803252fd