fix a segfault
fix another segfault
Document Ogita-Rump-Oishi algo.
Merge remote-tracking branch 'fredrik/trunk' into trunk

Conflicts:
	fmpz_mat/rq_d.c
Merge branch 'trunk' of git://github.com/wbhart/flint2 into lll
rename/remove macros in fmpz_lll.h