Protect gnc_mktime against bad dates.

git-svn-id: svn+ssh://svn.gnucash.org/repo/gnucash/trunk@23495 57a11ea4-9604-0410-9ed3-97b8803252fd
Protect against null account pointers in a couple of place to avoid asserts.

git-svn-id: svn+ssh://svn.gnucash.org/repo/gnucash/trunk@23496 57a11ea4-9604-0410-9ed3-97b8803252fd
Fix bug 653594 related to check printing.
This bug has two parts.  The original bug was that the wrong split is sometimes
used to print the check.  In the comments a second problem was mentioned:
sometimes the wrong split is omitted from the split list in formats that print
all the splits.

git-svn-id: svn+ssh://svn.gnucash.org/repo/gnucash/trunk@23497 57a11ea4-9604-0410-9ed3-97b8803252fd
Don't add a \n to the beginning of the split memo, account, or amount lists.
Pango seems to ignore it, but it really shouldn't be there.

git-svn-id: svn+ssh://svn.gnucash.org/repo/gnucash/trunk@23498 57a11ea4-9604-0410-9ed3-97b8803252fd